Reducing the need for manual start/end-pointing and trigger phrases

ABSTRACT

Systems and processes for selectively processing and responding to a spoken user input are provided. In one example, audio input containing a spoken user input can be received at a user device. The spoken user input can be identified from the audio input by identifying start and end-points of the spoken user input. It can be determined whether or not the spoken user input was intended for a virtual assistant based on contextual information. The determination can be made using a rule-based system or a probabilistic system. If it is determined that the spoken user input was intended for the virtual assistant, the spoken user input can be processed and an appropriate response can be generated. If it is instead determined that the spoken user input was not intended for the virtual assistant, the spoken user input can be ignored and/or no response can be generated.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/530,708, filed on Aug. 2, 2019, entitled REDUCING THE NEED FOR MANUALSTART/END-POINTING AND TRIGGER PHRASES, which claims priority to U.S.patent application Ser. No. 15/656,793, filed on Jul. 21, 2017, entitledREDUCING THE NEED FOR MANUAL START/END-POINTING AND TRIGGER PHRASES,which claims priority to U.S. patent application Ser. No. 14/502,737,filed on Sep. 30, 2014, entitled REDUCING THE NEED FOR MANUALSTART/END-POINTING AND TRIGGER PHRASES, which claims priority from U.S.Provisional Patent Application No. 62/005,760, filed on May 30, 2014,entitled REDUCING THE NEED FOR MANUAL START/END-POINTING AND TRIGGERPHRASES. The contents of each of these applications are herebyincorporated by reference in their entirety for all purposes.

FIELD

This relates generally to speech processing and, more specifically, tothe selective processing of spoken user inputs using contextual data.

BACKGROUND

Intelligent automated assistants (or virtual assistants) provide anintuitive interface between users and electronic devices. Theseassistants can allow users to interact with devices or systems usingnatural language in spoken and/or text forms. For example, a user canaccess the services of an electronic device by providing a spoken userinput to a virtual assistant associated with the electronic device. Thevirtual assistant can interpret the user's intent from the spoken userinput and operationalize the user's intent into tasks. The tasks canthen be performed by executing one or more functions of the electronicdevice and a relevant output can be returned to the user in naturallanguage form.

In order for a virtual assistant to properly process and respond to aspoken user input, the virtual assistant can first identify thebeginning and end of the spoken user input within a stream of audioinput using processes typically referred to as start-pointing andend-pointing, respectively. Conventional virtual assistants can identifythese points based on energy levels and/or acoustic characteristics ofthe received audio stream or manual identification by the user. Forexample, some virtual assistants can require users to input astart-point identifier by pressing a physical or virtual button beforespeaking to the virtual assistant or by uttering a specific triggerphrase before speaking to the virtual assistant in natural languageform. In response to receiving one of these start-point identifiers, thevirtual assistant can interpret subsequently received audio as being thespoken user input. While these techniques can be used to clearlyidentify spoken user input that is directed at the virtual assistant,interacting with the virtual assistant in this way can be unnatural ordifficult for the user. For example, in a back-and-forth conversationbetween the virtual assistant and the user, the user can be required toinput the start-point identifier (e.g., pressing a button or repeatingthe same trigger phrase) before each spoken user input.

SUMMARY

Systems and processes for operating a virtual assistant are disclosed.One example process can include receiving, at an electronic device, anaudio input, monitoring the audio input to identify a first spoken userinput, identifying the first spoken user input in the audio input, anddetermining whether to respond to the first spoken user input based oncontextual information associated with the first spoken user input. Theprocess can further include, in response to a determination to respondto the first spoken user input: generating a response to the firstspoken user input; and monitoring the audio input to identify a secondspoken user input. The process can further include, in response to adetermination not to respond to the first spoken user input, monitoringthe audio input to identify the second spoken user input withoutgenerating the response to the first spoken user input.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary environment in which a virtual assistantcan operate according to various examples.

FIG. 2 illustrates an exemplary user device according to variousexamples.

FIG. 3 illustrates an exemplary process for selectively processing andresponding to a spoken user input using contextual information accordingto various examples.

FIG. 4 illustrates another exemplary process for selectively processingand responding to a spoken user input using contextual informationaccording to various examples.

FIG. 5 illustrates a functional block diagram of an electronic deviceconfigured to selectively process and respond to a spoken user inputusing contextual information according to various examples.

DETAILED DESCRIPTION

In the following description of examples, reference is made to theaccompanying drawings in which it is shown by way of illustrationspecific examples that can be practiced. It is to be understood thatother examples can be used and structural changes can be made withoutdeparting from the scope of the various examples.

This relates to systems and processes for selectively processing andresponding to a spoken user input. In one example process, audio inputthat includes a spoken user input can be received at a user device. Thespoken user input can be identified from the audio input by identify astart-point and an end-point of the spoken user input. It can bedetermined whether or not the spoken user input was intended for avirtual assistant running on the user device and whether the virtualassistant should respond to the spoken user input based on contextualinformation. The determination can be made using a rule-based system ora probabilistic (e.g., machine learning) system. If it is determinedthat the spoken user input was intended for the virtual assistant andthat the virtual assistant should respond to the spoken user input, thespoken user input can be processed and an appropriate response can begenerated. If it is instead determined that the spoken user input wasnot intended for the virtual assistant, the spoken user input can beignored and/or no response can be generated. Using contextualinformation to determine whether or not a spoken user input was intendedfor the virtual assistant can advantageously allow a user to interactwith the virtual assistant without having to manually identify astart-point (e.g., by pressing a button or uttering a trigger phrase)before each spoken user input.

System Overview

FIG. 1 illustrates exemplary system 100 for implementing a virtualassistant according to various examples. The terms “virtual assistant,”“digital assistant,” “intelligent automated assistant,” or “automaticdigital assistant,” can refer to any information processing system thatinterprets natural language input in spoken and/or textual form to inferuser intent, and performs actions based on the inferred user intent. Forexample, to act on an inferred user intent, the system can perform oneor more of the following: identifying a task flow with steps andparameters designed to accomplish the inferred user intent; inputtingspecific requirements from the inferred user intent into the task flow;executing the task flow by invoking programs, methods, services, APIs,or the like; and generating output responses to the user in an audible(e.g., speech) and/or visual form.

A virtual assistant can be capable of accepting a user request at leastpartially in the form of a natural language command, request, statement,narrative, and/or inquiry. Typically, the user request seeks either aninformational answer or performance of a task by the virtual assistant.A satisfactory response to the user request can include either provisionof the requested informational answer, performance of the requestedtask, or a combination of the two. For example, a user can ask thevirtual assistant a question, such as “Where am I right now?” Based onthe user's current location, the virtual assistant can answer, “You arein Central Park.” The user can also request the performance of a task,for example, “Please remind me to call Mom at 4 PM today.” In response,the virtual assistant can acknowledge the request and then create anappropriate reminder item in the user's electronic schedule. Duringperformance of a requested task, the virtual assistant can sometimesinteract with the user in a continuous dialogue involving multipleexchanges of information over an extended period of time. There arenumerous other ways of interacting with a virtual assistant to requestinformation or performance of various tasks. In addition to providingverbal responses and taking programmed actions, the virtual assistantcan also provide responses in other visual or audio forms (e.g., astext, alerts, music, videos, animations, etc.) and possibly usingmultiple devices (e.g., output text to speech via a phone headset anddisplay text on a TV).

An example of a virtual assistant is described in Applicants' U.S.Utility application Ser. No. 12/987,982 for “Intelligent AutomatedAssistant,” filed Jan. 10, 2011, the entire disclosure of which isincorporated herein by reference.

As shown in FIG. 1, in some examples, a virtual assistant can beimplemented according to a client-server model. The virtual assistantcan include a client-side portion executed on a user device 102, and aserver-side portion executed on a server system 110. User device 102 caninclude any electronic device, such as a mobile phone, tablet computer,portable media player, desktop computer, laptop computer, PDA,television, television set-top box, wearable electronic device, or thelike, and can communicate with server system 110 through one or morenetworks 108, which can include the Internet, an intranet, or any otherwired or wireless public or private network. The client-side portionexecuted on user device 102 can provide client-side functionalities,such as user-facing input and output processing and communications withserver system 110. Server system 110 can provide server-sidefunctionalities for any number of clients residing on a respective userdevice 102.

Server system 110 can include one or more virtual assistant servers 114that can include a client-facing I/O interface 122, one or moreprocessing modules 118, data and model storage 120, and an I/O interfaceto external services 116. The client-facing I/O interface 122 canfacilitate the client-facing input and output processing for virtualassistant server 114. The one or more processing modules 118 can utilizedata and model storage 120 to determine the user's intent based onnatural language input and perform task execution based on inferred userintent. In some examples, virtual assistant server 114 can communicatewith external services 124, such as telephony services, calendarservices, information services, messaging services, navigation services,and the like, through network(s) 108 for task completion or informationacquisition. The I/O interface to external services 116 can facilitatesuch communications.

Server system 110 can be implemented on one or more standalone dataprocessing devices or a distributed network of computers. In someexamples, server system 110 can employ various virtual devices and/orservices of third party service providers (e.g., third-party cloudservice providers) to provide the underlying computing resources and/orinfrastructure resources of server system 110.

Although the functionality of the virtual assistant is shown in FIG. 1as including both a client-side portion and a server-side portion, insome examples, the functions of a the assistant can be implemented as astandalone application installed on a user device. In addition, thedivision of functionalities between the client and server portions ofthe virtual assistant can vary in different examples. For instance, insome examples, the client executed on user device 102 can be athin-client that provides only user-facing input and output processingfunctions, and delegates all other functionalities of the virtualassistant to a backend server.

User Device

FIG. 2 is a block diagram of a user-device 102 according to variousexamples. As shown, user device 102 can include a memory interface 202,one or more processors 204, and a peripherals interface 206. The variouscomponents in user device 104 can be together coupled by one or morecommunication buses or signal lines. User device 102 can further includevarious sensors, subsystems, and peripheral devices that are coupled tothe peripherals interface 206. The sensors, subsystems, and peripheraldevices gather information and/or facilitate various functionalities ofuser device 102.

For example, user device 102 can include a motion sensor 210, a lightsensor 212, and a proximity sensor 214 coupled to peripherals interface206 to facilitate orientation, light, and proximity sensing functions.One or more other sensors 216, such as a positioning system (e.g., a GPSreceiver), a temperature sensor, a biometric sensor, a gyroscope, acompass, an accelerometer, and the like, are also connected toperipherals interface 206, to facilitate related functionalities

In some examples, a camera subsystem 220 and an optical sensor 222 canbe utilized to facilitate camera functions, such as taking photographsand recording video clips. Communication functions can be facilitatedthrough one or more wired and/or wireless communication subsystems 224,which can include various communication ports, radio frequency receiversand transmitters, and/or optical (e.g., infrared) receivers andtransmitters. An audio subsystem 226 can be coupled to speakers 228 anda microphone 230 to facilitate voice-enabled functions, such as voicerecognition, voice replication, digital recording, and telephonyfunctions.

In some examples, user device 102 can further include an I/O subsystem240 coupled to peripherals interface 206. I/O subsystem 240 can includea touch screen controller 242 and/or other input controller(s) 244.Touch-screen controller 242 can be coupled to a touch screen 246. Touchscreen 246 and the touch screen controller 242 can, for example, detectcontact and movement or break thereof using any of a plurality of touchsensitivity technologies, such as capacitive, resistive, infrared,surface acoustic wave technologies, proximity sensor arrays, and thelike. Other input controller(s) 244 can be coupled to otherinput/control devices 248, such as one or more buttons, rocker switches,a thumb-wheel, an infrared port, a USB port, and/or a pointer devicesuch as a stylus.

In some examples, user device 102 can further include a memory interface202 coupled to memory 250. Memory 250 can include any electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, a portable computer diskette (magnetic), a randomaccess memory (RAM) (magnetic), a read-only memory (ROM) (magnetic), anerasable programmable read-only memory (EPROM) (magnetic), a portableoptical disc such as CD, CD-R, CD-RW, DVD, DVD-R, or DVD-RW, or flashmemory such as compact flash cards, secured digital cards, USB memorydevices, memory sticks, and the like. In some examples, a non-transitorycomputer-readable storage medium of memory 250 can be used to storeinstructions (e.g., for performing process 300 and/or 400, describedbelow) for use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions. In other examples, the instructions (e.g.,for performing process 300 and/or 400, described below) can be stored ona non-transitory computer-readable storage medium of server system 110,or can be divided between the non-transitory computer-readable storagemedium of memory 250 and the non-transitory computer-readable storagemedium of server system 110. In the context of this document, a“non-transitory computer readable storage medium” can be any medium thatcan contain or store the program for use by or in connection with theinstruction execution system, apparatus, or device.

In some examples, the memory 250 can store an operating system 252, acommunication module 254, a graphical user interface module 256, asensor processing module 258, a phone module 260, and applicationsmodule 262. Operating system 252 can include instructions for handlingbasic system services and for performing hardware dependent tasks.Communication module 254 can facilitate communicating with one or moreadditional devices, one or more computers and/or one or more servers.Graphical user interface module 256 can facilitate graphic userinterface processing. Sensor processing module 258 can facilitate sensorrelated processing and functions. Phone module 260 can facilitatephone-related processes and functions. Applications module 262 canfacilitate various functionalities of user applications, such aselectronic-messaging, web browsing, media processing, navigation,imaging and/or other processes and functions.

As described herein, memory 250 can also store client-side virtualassistant instructions (e.g., in a virtual assistant client module 264)and various user data 266 (e.g., user-specific vocabulary data,preference data, and/or other data such as the user's electronic addressbook, to-do lists, shopping lists, etc.) to provide the client-sidefunctionalities of the virtual assistant.

In various examples, virtual assistant client module 264 can be capableof accepting voice input (e.g., speech input), text input, touch input,and/or gestural input through various user interfaces (e.g., I/Osubsystem 240, audio subsystem 226, or the like) of user device 104.Virtual assistant client module 264 can also be capable of providingoutput in audio (e.g., speech output), visual, and/or tactile forms. Forexample, output can be provided as voice, sound, alerts, text messages,menus, graphics, videos, animations, vibrations, and/or combinations oftwo or more of the above. During operation, virtual assistant clientmodule 264 can communicate with the virtual assistant server usingcommunication subsystems 224. Additionally, virtual assistant clientmodule 264 can communicate with other devices, such as home automationequipment, and can thus have a physical effect on the physical world(e.g., unlocking a door) or can be embedded in such devices.

In some examples, virtual assistant client module 264 can utilize thevarious sensors, subsystems, and peripheral devices to gather additionalinformation from the surrounding environment of user device 102 toestablish a context associated with a user, the current userinteraction, and/or the current user input. In some examples, virtualassistant client module 264 can provide the contextual information or asubset thereof with the user input to the virtual assistant server tohelp infer the user's intent. The virtual assistant can also use thecontextual information to determine how to prepare and deliver outputsto the user. As discussed in greater detail below, the contextualinformation can further be used by user device 102 or server system 110to determine whether or not a spoken user input is intended for thevirtual assistant and to determine an appropriate response.

In some examples, the contextual information that accompanies the userinput can include sensor information, such as lighting, ambient noise,ambient temperature, images or videos of the surrounding environment,distance to another object, and the like. The contextual information canfurther include information associated with the physical state of userdevice 102 (e.g., device orientation, device location, devicetemperature, power level, speed, acceleration, motion patterns, cellularsignals strength, etc.) or the software state of user device 102 (e.g.,running processes, installed programs, past and present networkactivities, background services, error logs, resources usage, front-mostapplication, etc.). Any of these types of contextual information can beprovided to the virtual assistant server as contextual informationassociated with a user input. Additionally, the contextual informationcan further include biometric user data, such as heart rate, handtemperature, voice quality, facial expression, etc.

In some examples, virtual assistant client module 264 can selectivelyprovide information (e.g., user data 266) stored on user device 102 inresponse to requests from the virtual assistant server. Virtualassistant client module 264 can also elicit additional input from theuser via a natural language dialogue or other user interfaces uponrequest by virtual assistant server 114. Virtual assistant client module264 can pass the additional input to virtual assistant server 114 tohelp virtual assistant server 114 in intent inference and/or fulfillmentof the user's intent expressed in the user request.

In various examples, memory 250 can include additional instructions orfewer instructions. Furthermore, various functions of user device 102can be implemented in hardware and/or in firmware, including in one ormore signal processing and/or application specific integrated circuits.

Processes for Operating the Virtual Assistant

FIG. 3 illustrates an exemplary process 300 that can be performed toselectively process and respond to a user input (e.g., a spoken userinput) using contextual information according to various examples. Insome examples, process 300 can be performed using a system similar oridentical to system 100, shown in FIG. 1.

At block 302, an audio input can be received at a user device. The audioinput can include any detectable sound, such as music, a user's voice,background noise, a combination thereof, or the like. In some examples,a user device (e.g., user device 102) can receive audio input thatincludes a user's natural language speech via a microphone (e.g.,microphone 230). The microphone can convert the audio input into ananalog or digital representation and provide the audio data to one ormore processors (e.g., processor(s) 204). While shown as being discretefrom the other blocks of process 300, it should be appreciated that, insome examples, audio input can continue to be received at block 302while some or all of the other blocks of process 300 are beingperformed.

At block 304, the audio input received at block 302 can be monitored toidentify a segment of the audio input that includes or potentiallyincludes a spoken user input. In some examples, this can includemonitoring one or more characteristics of the audio input to identify astart-point and an end-point of the spoken user input within the audioinput. The start and end-points can be identified using any knownstart/end-pointing algorithm, such as those relying on energy featuresof the audio input (e.g., short-time energy and zero-crossing rate) todistinguish user speech from background noise in the audio input. Insome examples, the processor(s) of the user device can analyze theenergy of the audio data received from the device's microphone toidentify segments of the audio input that are sufficiently high inenergy and have zero-crossing rates characteristic of user speech. Inother examples, the user device can transmit the audio data to a remoteserver (e.g., virtual assistant server 114) capable of determining thestart and end-points of the spoken user input.

In some examples, block 304 can further include performing aspeech-to-text conversion operation on the detected spoken user inputeither locally on the device or by transmitting the audio data to aremote server capable of such an operation. In other examples, block 304may not include performing a speech-to-text conversion operation.Instead, the speech-to-text conversion operation can be performed atblock 312 after determining that the virtual assistant should respond tothe spoken user input at block 308.

At block 306, it can be determined whether or not a spoken user inputwas identified while monitoring the audio input at block 304. If nospoken user input was identified, the process can return to block 304.If, however, a spoken user input was identified, the process can proceedto block 308.

At block 308, it can be determined whether or not the virtual assistantshould respond to the spoken user input by determining whether or notthe spoken user input identified at block 304 was intended for thevirtual assistant (e.g., the user directed the spoken user input at thevirtual assistant and expects the virtual assistant to perform a task orprovide a response based on the spoken user input) based on contextualinformation. Various example sources of contextual information that canbe used at block 308 to determine whether or not the spoken user inputwas intended for the virtual assistant are described below. Block 308can be performed by the user device, a remote server (e.g., virtualassistant server 114), or a combination thereof.

In some examples, a probabilistic system can be used to determinewhether or not the virtual assistant should respond to the spoken userinput by determining a likelihood or confidence score that the userintended for the spoken user input to be directed at the virtualassistant. The probabilistic system can include a machine learningsystem or classifiers, such as neural networks. Additionally, theprobabilistic system can learn and adapt to the user using a feedbackloop. In these probabilistic system examples, the likelihood orconfidence score can include a numerical or other representation of acalculated probability that the user intended for the spoken user inputto be directed at the virtual assistant. The calculated likelihood orconfidence score can then be compared to a threshold value to determinewhether or not the virtual assistant should respond to the spoken userinput. For example, if the calculated likelihood or confidence score isgreater than the threshold value, it can be determined that the spokenuser input was intended for the virtual assistant. If, however, thecalculated likelihood or confidence score is not greater than thethreshold value, it can be determined that the spoken user input was notintended for the virtual assistant.

The likelihood or confidence score can be determined in any number ofways. For example, the determination can generally include summingpositive, negative, and/or neutral contributions from any number ofdifferent types of contextual information. For example, the likelihoodor confidence score can be calculated using the general formula ofP=C₁+C₂+C₃+ . . . +C_(N), where P represents the likelihood orconfidence score that the spoken user input was intended for the userdevice and C₁ . . . C_(N) can be positive, negative, or zero valuesrepresenting the positive, negative, or neutral contributions to thelikelihood or confidence score from the N different types of contextualinformation. A positive contribution can represent a type of contextualinformation that suggests that the spoken user input was intended forthe virtual assistant, a negative contribution can represent a type ofcontextual information that suggests that the spoken user input was notintended for the virtual assistant, and a neutral contribution canrepresent a type of contextual information that is neutral regarding thelikelihood that the spoken user input was intended for the virtualassistant. Thus, a large P value can indicate that the spoken user inputwas likely intended for the virtual assistant, while small or negative Pvalues can indicate that the spoken user input was likely not intendedfor the virtual assistant. The weight or value that each contextualinformation contribution adds to the likelihood or confidence scoredetermination can be uniform or non-uniform. Additionally, the weight orvalue that each contribution adds to the likelihood or confidence scoredetermination can depend on the value of the particular type ofcontextual information. For example, if contribution C₁ depends on thevolume of the user's voice, the sign (e.g., +/−) and/or magnitude of C₁can depend on a numerical representation of the volume of the user'svoice.

While an example probabilistic system is provided above, it should beappreciated that modifications can be made to the described systemand/or other scoring conventions can be used. For example, a positivecontribution can instead represent a type of contextual information thatsuggests that the spoken user input was not intended for the virtualassistant and a negative contribution can instead represent a type ofcontextual information that suggests that the spoken user input wasintended for the virtual assistant. In other examples, the contributionsfrom the different types of contextual information can all be positive,with larger positive values indicating that the contextual informationsuggests that the spoken user input was intended (alternatively, notintended) for the virtual assistant. In yet other examples, thecontributions from the different types of contextual information can allbe negative, with larger negative values indicating that the contextualinformation suggests that the spoken user input was intended(alternatively, not intended) for the virtual assistant.

In other examples, a rule-based system can be used to determine whetheror not the virtual assistant should respond to the spoken user input byevaluating any number of conditional rules that are based on thecontextual information to determine whether or not the spoken user inputwas intended for the virtual assistant. In some examples, the rule-basedsystems can include the use of a decision tree. In other examples, therules used by the rule-based system can be learned based on userbehavior. To illustrate an example rule-based system, a first rule caninclude the condition that if the user is facing the device and thevolume of the user's voice is above a threshold volume, then it can bedetermined that the user intended for the spoken user input to bedirected at the virtual assistant. A second rule can include thecondition that if, according to the user's calendar, the user is in ameeting, then it can be determined that the user did not intend for thespoken user input to be directed at the virtual assistant. Other similarrules containing any number of conditions that depend on any type ofcontextual information can be used to cause the device to determine thatthe spoken user input was or was not intended for the virtual assistant.In some examples, the rules can be ranked, such that if multiple rulesevaluate to being true, the outcome of the higher ranking rule can beused as the result of the determination operation performed at block308. Additionally, in some examples, if none of the rules evaluate tobeing true, a default determination that the spoken user input wasintended for the virtual assistant (or that the spoken user input wasnot intended for the virtual assistant) can be made.

At block 310, if it was determined at block 308 that the virtualassistant should not respond to the spoken user input because the spokenuser input was not intended for the virtual assistant, the process canreturn to block 304 to monitor the audio input for a spoken user input.In some examples, process 300 can proceed from block 310 to block 304without generating a response the spoken user input. For example,process 300 can proceed from block 310 to block 304 without performingone or more of performing speech-to-text conversion, inferring userintent, identifying a task flow with steps and parameters designed toaccomplish the inferred user intent, inputting specific requirementsfrom the inferred user intent into the task flow, executing the taskflow by invoking programs, methods, services, APIs, or the like, andgenerating output responses to the user in an audible (e.g., speech)and/or visual form. If it was instead determined at block 308 that thevirtual assistant should respond to the spoken user input because thespoken user input was intended for the virtual assistant, the processcan proceed to block 312.

At block 312, a response to the spoken user input can be generated bythe user device and/or a remote server. In some examples, generating aresponse to the spoken user input can include one or more of performingspeech-to-text conversion, inferring user intent, identifying a taskflow with steps and parameters designed to accomplish the inferred userintent, inputting specific requirements from the inferred user intentinto the task flow, executing the task flow by invoking programs,methods, services, APIs, or the like, and generating output responses tothe user in an audible (e.g., speech) and/or visual form. For example,block 312 can include performing an operation requested by the user(e.g., opening an application, sending a message, calling a contact,performing a search query, creating a calendar appointment, or thelike), providing information requested by the user (e.g., returning theresult of a search query), performing an action that causes a change inthe physical environment (e.g., communicating with a home appliance tolock a door), or the like. The operations can be performed locally onthe user device, by transmitting data to a remote server for processing,or a combination thereof. After processing the spoken user input toprovide an appropriate response at block 312, the process can return toblock 304.

Using process 300, a virtual assistant implemented by a user device canselectively ignore or respond to spoken user inputs in a way that allowsa user to speak to the virtual assistant in natural language withouthaving to manually enter a start-point identifier, such as by pressing aphysical or virtual button before speaking to the virtual assistant orby uttering a specific trigger phrase (e.g., a predetermined word orsequence of words, such as “Hey Siri”) before speaking to the virtualassistant in natural language. In some examples, process 300 can be usedto process all spoken user inputs received by user device 102.

To illustrate the operation of FIG. 3, one example interaction between auser and the virtual assistant can begin by the user verbally asking aquestion, such as “what time is it in New York?”, without the userhaving to manually enter a start-point identifier, such as by pressing aphysical or virtual button before speaking to the virtual assistant orby uttering a specific trigger phrase (e.g., a predetermined word orsequence of words, such as “Hey Siri”). At block 302, the user devicecan receive an audio input that includes the user's question. At block304, the audio input can be monitored to detect a spoken user input.Since the audio input included the user's question, it can be determinedat block 306 that the spoken user input was identified. At block 308, itcan be determined, based on contextual information associated with theidentified spoken user input, whether the virtual assistant shouldrespond to the user's question. In this example, it can be determined(using either the rule-based or probabilistic system) that the virtualassistant should respond to the user's question because the contextualinformation indicates that the user was looking at the user device whilespeaking the question and that the volume of the user's voice was abovea threshold volume. Thus, the process can proceed to block 310 and 312,where a response to the user's question can be generated. For example,at block 312, the user's question can be processed to determine theuser's intent, identify tasks to be performed, and execute functions todetermine and display a time of “5:01 p.m.” in response to the user'squery. Process 300 can then return to block 304.

The user can then verbally ask another question, such as “what is theweather there?”, without the user having to manually enter a start-pointidentifier, such as by pressing a physical or virtual button beforespeaking to the virtual assistant or by uttering a specific triggerphrase (e.g., a predetermined word or sequence of words, such as “HeySiri”). The audio input being received by the user device and thatincludes the user's second question can be monitored at block 304. Sincethe audio input included the user's second question, it can bedetermined at block 306 that the spoken user input was identified. Atblock 308, it can be determined, based on contextual informationassociated with the identified spoken user input, whether the virtualassistant should respond to the user's question. In this example, it canbe determined (using either the rule-based or probabilistic system) thatthe virtual assistant should respond to the user's question because thecontextual information indicates that the user asked the second questionwithin a threshold length of time from receiving an answer to the firstquestion, suggesting that the second question was part of the sameconversation. Thus, the process can proceed to block 310 and 312, wherea response to the user's question can be generated. For example, atblock 312, the user's question can be processed to determine the user'sintent, identify tasks to be performed, and execute functions todetermine and display a message saying that “the weather is sunny” inresponse to the user's query. Process 300 can then return to block 304to monitor the audio input for additional spoken user inputs.

In other examples, user device 102 can require that a start-pointidentifier be manually entered by the user prior to process 300 beinginvoked. For example, a user can be required to utter a trigger phraseor press a physical or virtual button before first speaking to thevirtual assistant. In response to the manual start-point identifier,process 300 can be performed as described above and subsequent spokenuser inputs can be processed without requiring user to enter additionalstart-point identifiers. FIG. 4 shows an example process for performingthis modified interaction.

At block 402, a start-point identifier can be received. The start-pointidentifier can include a trigger phrase spoken by the user, a selectionof a physical or virtual button, or other manual input received from theuser. At block 404, an audio input can be received in a manner similaror identical to block 302, described above. At block 406, an initialspoken user input can be identified from the audio input received atblock 404 by identifying an end-point for the first spoken user input.The end-point can be identified based on energy features of the audioinput, as described above. At block 408, a response to the first spokenuser input can be generated in a manner similar or identical to block312, described above. However, in contrast to block 312, block 408 canbe performed without determining whether or not the virtual assistantshould respond to the first spoken user input in a manner similar tothat of block 308, since a manual start-point identifier was received atblock 402. After generating the response to the first spoken user inputat block 408, the process can proceed to block 304. In some examples,block 302 can be omitted since the audio input was previously receivedat block 404. Blocks 304, 306, 308, 310, and 312 can be repeatedlyperformed, as described above with respect to FIG. 3.

In some examples, once block 304 is invoked in process 400, blocks 304,306, 308, 310, and 312 can continue to be performed for all subsequentspoken user inputs. In other examples, performance of blocks 304, 306,308, 310, and 312 can be stopped if no spoken user input is received(e.g., at blocks 304 and 306) for greater than a threshold length oftime, resulting in the user having to enter a start-point identifier atblock 402 before inputting the next spoken user input.

Using process 400, a virtual assistant implemented by a user device canonly require a user to enter a manual start-point identifier once, andcan allow the virtual assistant to selectively ignore or respond tosubsequent spoken user inputs without requiring the user to repeatedlyenter a manual start-point identifier before each subsequent spoken userinput.

To illustrate the operation of FIG. 4, one example interaction between auser and the virtual assistant can begin by the user manually entering astart-point identifier, such as by pressing a physical or virtual buttonbefore speaking to the virtual assistant or by uttering a specifictrigger phrase (e.g., a predetermined word or sequence of words, such as“Hey Siri”). The start-point identifier can be received at block 402.The user can then verbally ask a question, such as “what time is it inNew York?” The user device can receive an audio input that includes theuser's question at block 404. At block 406, the spoken user input can beidentified from the audio input by identifying an end-point of theuser's question. At block 408, a response to the user's question can begenerated without performing a determination step similar to block 308,since the user manually identified the input as being directed at thevirtual assistant at block 402. For example, at block 408, the user'squestion can be processed to determine the user's intent, identify tasksto be performed, and execute functions to determine and display a timeof “5:01 p.m.” in response to the user's query. Process 400 can thenproceed to block 304.

The user can then verbally ask another question, such as “what is theweather like there?”, without the user having to manually enter astart-point identifier, such as by pressing a physical or virtual buttonbefore speaking to the virtual assistant or by uttering a specifictrigger phrase (e.g., a predetermined word or sequence of words, such as“Hey Siri”). The audio input being received by the user device and thatincludes the user's second question can be repeatedly monitored atblocks 304 and 306. Since the audio input included the user's secondquestion, it can be determined at block 306 that the spoken user inputwas identified. At block 308, it can be determined, based on contextualinformation associated with the identified spoken user input, whetherthe virtual assistant should respond to the user's question. In thisexample, it can be determined (using either the rule-based orprobabilistic system) that the virtual assistant should respond to theuser's question because the contextual information indicates that theuser asked the second question within a threshold length of time fromreceiving an answer to the first question, suggesting that the secondquestion was part of the same conversation. Thus, the process canproceed to block 310 and 312, where a response to the user's questioncan be generated. For example, at block 312, the user's question can beprocessed to determine the user's intent, identify tasks to beperformed, and execute functions to determine and display a messagesaying that “the weather is sunny” in response to the user's query.Process 300 can then return to block 304 to monitor the audio input foradditional spoken user inputs.

In some examples, while process 300 or blocks 304, 306, 308, 310, and312 of process 400 are being performed, a visual indicator can bedisplayed on a display of user device 102 to indicate that user device102 is capable of accepting a spoken user input in natural language formwithout the use of trigger phrases or other manual inputs to indicatethat a spoken user input is intended for user device 102.

Additionally, while the blocks of processes 300 and 400 are shown anddescribed in a particular order, it should be appreciated that theblocks of processes 300 and 400 can be performed in other orders or atthe same time. For example, in process 300, user device 102 cancontinually receive an audio input at block 302 while some or all ofblocks 304, 306, 308, 310, and 312 can be performed. Similarly, inprocess 400, user device 102 can continually receive an audio input atblock 404 while some or all of blocks 304, 306, 308, 310, 312, 406, and408 can be performed.

It should be appreciated that the blocks of processes 300 and 400 can beperformed on user device 102, server system 110, or a combination ofuser device 102 and server system 110. For instance, in some examples,all blocks of process 300 or 400 can be performed on user device 102. Inother examples, all blocks of process 300 or 400 can be performed atserver system 110. In yet other examples, some blocks of process 300 or400 can be performed at user device 102, while other blocks of process300 or 400 can be performed at server system 110.

Contextual Information

As discussed above, any number of types of contextual information, whichcan also include the features used by a classifier or machine learningsystem, can be used by processor(s) 204 and/or server system 110 atblock 308 of process 300 or 400 to determine whether or not a spokenuser input was intended for a virtual assistant. Described below aresome example types of contextual information and ways that these typesof contextual information can be used to determine whether or not aspoken user input was intended for a virtual assistant at block 308 ofprocess 300.

In some examples, the contextual information can include time data froma clock or timer of user device 102. The time data can represent alength of time between any desired two or more events. For example, thetime data can represent a length of time between the spoken user inputbeing received and a time that a previous user input, such as a buttonpress, mouse click, screen touch, previous spoken user input, or thelike, was received. Generally, in some examples, a shorter length oftime between the two events can be indicative that the user was morelikely to have intended for the current spoken user input to be directedat the virtual assistant, while a longer length of time between eventscan be indicative that the user was less likely to have intended for thecurrent spoken user input to be directed at the virtual assistant.However, in other examples, a longer length of time between the twoevents can be indicative that the user was more likely to have intendedfor the current spoken user input to be directed at the virtualassistant, while a shorter length of time between events can beindicative that the user was less likely to have intended for thecurrent spoken user input to be directed at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the length of time between consecutive spoken userinputs is less than a threshold duration, then it can be determined thatthe user intended for the current spoken user input to be directed atthe virtual assistant. Another rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the length of time between consecutive spoken userinputs is greater than or equal to the threshold duration, it can bedetermined that the user did not intend for the current spoken userinput to be directed at the virtual assistant.

In one example probabilistic system, the length of time betweenconsecutive spoken user inputs can be used to calculate a positive,negative, or neutral contribution to a final likelihood or confidencescore, where the value of the contribution can have a linear ornon-linear relationship with the value of the length of time. Forexample, a length of time less than a threshold duration can contributea positive value to the final likelihood or confidence score, where themagnitude of the positive value can be greater for shorter lengths oftime. Similarly, a length of time greater than or equal to the thresholdduration can contribute a zero or negative value to the final likelihoodor confidence score, where the magnitude of the negative value can begreater for longer lengths of time. In some examples, the length of timebetween consecutive spoken user inputs can be used to train a machinelearning system of the probabilistic system.

In some examples, the contextual information can include conversationhistory data from memory 250 or another storage device located within orremote from user device 102. The conversation history data can includeany number of previous spoken user inputs received from the user and/orresponses generated and provided to the user by the user device. In someexamples, the previously received spoken user inputs can be comparedwith the current spoken user input to determine if the current spokenuser input is the same as a previously received spoken user input. Inthese examples, a match between the previous and current spoken userinput (e.g., caused by the user repeating him or herself) can beindicative that the user was more likely to have intended for thecurrent spoken user input to be directed at the virtual assistant, whileno match between the previous and current spoken user input can beindicative that the user was less likely to have intended for thecurrent spoken user input to be directed at the virtual assistant or canbe neutral regarding the likelihood that the user intended for thecurrent spoken user input to be directed at the virtual assistant. Insome examples, the user repeating him or herself can be used in afeedback loop to train a machine learning system of the probabilisticsystem.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the current spoken user input is the same as ormatches the previously received spoken user input, then it can bedetermined that the user intended for the current spoken user input tobe directed at the virtual assistant. Another rule that can be used(alone, in combination with other rules, or as one of multipleconditions in other rules) is that if the current spoken user input isnot the same as the previously received spoken user input, it can bedetermined that the user did not intend for the current spoken userinput to be directed at the virtual assistant.

In one example probabilistic system, a determination that a previouslyreceived spoken user input is the same as or matches the current spokenuser input can contribute a positive value to the final likelihood orconfidence score, while no match between the previously received spokenuser input and the current spoken user input can contribute a zero or anegative value to the final likelihood or confidence score. Themagnitude of the positive or negative contribution can be adjusted basedon the overall system design.

In other examples, a semantic similarity analysis can be performed onthe current spoken user input and some or all of the conversationhistory data. In some examples, this can include computing a similarityof the determined user intents (e.g., the result of the natural languageinterpretation phase that takes the form of a tuple <command,parameters>). In other examples, performing the semantic similarityanalysis to determine the semantic distance can include determining anedit distance combined with a similarity matrix. In these examples, asemantic distance between the current spoken user input and one or moreof the previously received spoken user inputs or responses generated andprovided to the user by the user device can be determined and used todetermine the likelihood or confidence score that the spoken user inputwas intend for the virtual assistant at block 308. In these examples, asmall semantic distance between the current spoken user input and one ormore of the previously received spoken user inputs (e.g., theimmediately preceding spoken user input) and/or one or more of theresponses generated and provided to the user by the user device can beindicative that the user was more likely to have intended for thecurrent spoken user input to be directed at the virtual assistant, whilea large semantic distance between the current spoken user input and oneor more of the previously received spoken user inputs (e.g., theimmediately preceding spoken user input) and/or one or more of theresponses generated and provided to the user by the user device can beindicative that the user was less likely to have intended for thecurrent spoken user input to be directed at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if a semantic distance between the current spoken userinput and one or more previous spoken user inputs or responses generatedby the user device is less than a threshold value, then it can bedetermined that the user intended for the current spoken user input tobe directed at the virtual assistant. Another rule that can be used(alone, in combination with other rules, or as one of multipleconditions in other rules) is that if the semantic distance between thecurrent spoken user input and one or more previous spoken user inputs orresponses generated by the user device is greater than or equal to thethreshold value, it can be determined that the user did not intend forthe current spoken user input to be directed at the virtual assistant.

In one example probabilistic system, a semantic distance between thecurrent spoken user input and one or more previous spoken user inputs orresponses generated by the user device can be used to calculate apositive, negative, or neutral contribution to a final likelihood orconfidence score, where the value of the contribution can have a linearor non-linear relationship with the semantic distance. For example, asemantic distance that is less than a threshold value can contribute apositive value to the final likelihood or confidence score, where themagnitude of the positive value can be greater for smaller semanticdistances. Similarly, a semantic distance that is greater than or equalto the threshold value can contribute a zero or negative value to thefinal likelihood or confidence score, where the magnitude of thenegative value can be greater for larger semantic distances.

In some examples, the contextual information can include distance datafrom a distance sensor, such as proximity sensor 214, of user device102. The distance data can represent a spatial distance between the userdevice and the user (e.g., a distance between the user device and theuser's face). Generally, in some examples, a shorter distance betweenthe user device and the user can be indicative that the user was morelikely to have intended for the current spoken user input to be directedat the virtual assistant, while a longer distance between the userdevice and the user can be indicative that the user was less likely tohave intended for the current spoken user input to be directed at thevirtual assistant. However, in other examples, a longer distance betweenthe user device and the user can be indicative that the user was morelikely to have intended for the current spoken user input to be directedat the virtual assistant, while a shorter distance between the userdevice and the user can be indicative that the user was less likely tohave intended for the current spoken user input to be directed at thevirtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the distance between the user device and the user isless than a threshold distance, then it can be determined that the userintended for the current spoken user input to be directed at the virtualassistant. Another rule that can be used (alone, in combination withother rules, or as one of multiple conditions in other rules) is that ifthe distance between the user device and the user is greater than orequal to the threshold distance, it can be determined that the user didnot intend for the current spoken user input to be directed at thevirtual assistant.

In one example probabilistic system, the distance between the userdevice and the user can be used to calculate a positive, negative, orneutral contribution to a final likelihood or confidence score, wherethe value of the contribution can have a linear or non-linearrelationship with the value of the distance between the user device andthe user. For example, a distance less than a threshold distance cancontribute a positive value to the final likelihood or confidence score,where the magnitude of the positive value can be greater for shorterdistances. Similarly, a distance greater than or equal to the thresholddistance can contribute a zero or negative value to the final likelihoodor confidence score, where the magnitude of the negative value can begreater for greater distances.

In some examples, the contextual information can include audio data fromaudio subsystem 226. The audio data can include a representation of avolume of the spoken user input. Generally, in some examples, a highervolume of the spoken user input can be indicative that the user was morelikely to have intended for the current spoken user input to be directedat the virtual assistant, while a lower volume of the spoken user inputcan be indicative that the user was less likely to have intended for thecurrent spoken user input to be directed at the virtual assistant.However, in other examples, a lower volume of the spoken user input canbe indicative that the user was more likely to have intended for thecurrent spoken user input to be directed at the virtual assistant, whilea higher volume of the spoken user input can be indicative that the userwas less likely to have intended for the current spoken user input to bedirected at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the volume of the spoken user input was greater than athreshold volume, then it can be determined that the user intended forthe current spoken user input to be directed at the virtual assistant.Another rule that can be used (alone, in combination with other rules,or as one of multiple conditions in other rules) is that if the volumeof the spoken user input was less than or equal to the threshold volume,it can be determined that the user did not intend for the current spokenuser input to be directed at the virtual assistant.

In one example probabilistic system, the volume of the spoken user inputcan be used to calculate a positive, negative, or neutral contributionto a final likelihood or confidence score, where the value of thecontribution can have a linear or non-linear relationship with the valueof the volume of the spoken user input. For example, a volume greaterthan a threshold volume can contribute a positive value to the finallikelihood or confidence score, where the magnitude of the positivevalue can be greater for higher volumes. Similarly, a volume less thanor equal to the threshold volume can contribute a zero or negative valueto the final likelihood or confidence score, where the magnitude of thenegative value can be greater for lower volumes.

In some examples, the contextual information can include audio data fromaudio subsystem 226. The audio data can include a representation of avolume of the spoken user input. In some examples, if a previous spokeninput was ignored and the volume of a current spoken user input ishigher than the previous spoken user input, this can be indicative thatthe user was more likely to have intended for the current spoken userinput to be directed at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the volume of the current spoken user input is greaterthan a volume of the previous spoken user input, then it can bedetermined that the user intended for the current spoken user input tobe directed at the virtual assistant. Another rule that can be used(alone, in combination with other rules, or as one of multipleconditions in other rules) is that if the volume of the current spokenuser input is less than or equal to the volume of the previous spokenuser input, it can be determined that the user did not intend for thecurrent spoken user input to be directed at the virtual assistant.

In one example probabilistic system, the volume of the spoken user inputcan be used to calculate a positive, negative, or neutral contributionto a final likelihood or confidence score, where the value of thecontribution can have a linear or non-linear relationship with the valueof the volume of the spoken user input. For example, if the volume ofthe current spoken user input is greater than a volume of an immediatelyprevious spoken user input, a positive value to the final likelihood orconfidence score can be added. Similarly, if the volume of the currentspoken user input is less than a volume of an immediate previous spokenuser input, a zero or negative value can be added to the finallikelihood or confidence score.

In other examples, the audio data can be analyzed using known speakerrecognition techniques to determine a number of distinct speakers thatare near or within audio range of the user device. In these examples, adetermination that more than one speaker is present can be indicativethat the user was less likely to have intended for the current spokenuser input to be directed at the virtual assistant (and was insteadspeaking to another person nearby), while a determination that only onespeaker is present can be indicative that the user was more likely tohave intended for the current spoken user input to be directed at thevirtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if it is determined that more than one speaker waspresent when the spoken user input was received, then it can bedetermined that the user did not intend for the current spoken userinput to be directed at the virtual assistant. Another rule that can beused (alone, in combination with other rules, or as one of multipleconditions in other rules) is that if it is determined that only onespeaker was present when the spoken user input was received, it can bedetermined that the user intended for the current spoken user input tobe directed at the virtual assistant.

In one example probabilistic system, a determination that more than onespeaker was present when the spoken user input was received cancontribute a negative value to the final likelihood or confidence score,while a determination that only one speaker was present when the spokenuser input was received can contribute a zero or a positive value to thefinal likelihood or confidence score. The magnitude of the positive ornegative contribution can be adjusted based on the overall systemdesign.

In yet other examples, the audio data can be analyzed using knownspeaker recognition techniques to determine whether or not the spokenuser input was received from a known or an authorized user of the userdevice (e.g., the owner of the device) or from the same speaker as apreviously received spoken user input. In these examples, adetermination that the spoken user input was received from the known orauthorized user or from the same speaker as a previously received spokenuser input can be indicative that the user was more likely to haveintended for the current spoken user input to be directed at the virtualassistant, while a determination that the spoken user input was notreceived from the known or authorized user or from the same speaker as apreviously received spoken user input can be indicative that the userwas less likely to have intended for the current spoken user input to bedirected at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if it is determined that the spoken user input wasreceived from the known or authorized user or from the same speaker as apreviously received spoken user input, then it can be determined thatthe user intended for the current spoken user input to be directed atthe virtual assistant. Another rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if it is determined that the spoken user input was notreceived from the known or authorized user or from the same speaker as apreviously received spoken user input, it can be determined that theuser did not intend for the current spoken user input to be directed atthe virtual assistant.

In one example probabilistic system, a determination that the spokenuser input was received from the known or authorized user or from thesame speaker as a previously received spoken user input can contribute apositive value to the final likelihood or confidence score, while adetermination that the spoken user input was not received from the knownor authorized user or from the same speaker as a previously receivedspoken user input can contribute a zero or a negative value to the finallikelihood or confidence score. The magnitude of the positive ornegative contribution can be adjusted based on the overall systemdesign.

In some examples, the contextual information can include image data fromcamera subsystem 220 of user device 102. The image data can represent animage or video captured by camera subsystem 220. In some examples, theimage data can be used to estimate a distance between the user deviceand the user. For example, the size of the user within the image can beused to estimate the distance between the user device and the user. Theestimated distance between the user device and the user can be used in arule-based or probabilistic system in a manner similar or identical tothe distance data from proximity sensor 214, described above.

In other examples, the image data can be analyzed (e.g., using knowneye-tracking techniques) to determine whether or not the user is lookingat or facing the user device when the spoken user input was received. Inthese examples, a determination that the user was looking at the userdevice when the spoken user input was received can be indicative thatthe user is more likely to have intended for the current spoken userinput to be directed at the virtual assistant, while a determinationthat the user was not looking at the user device when the spoken userinput was received can be indicative that the user was less likely tohave intended for the current spoken user input to be directed at thevirtual assistant or can be neutral regarding the likelihood that theuser intended for the current spoken user input to be directed at thevirtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if it is determined that the user was looking at the userdevice when the spoken user input was received, then it can bedetermined that the user intended for the current spoken user input tobe directed at the virtual assistant. Another rule that can be used(alone, in combination with other rules, or as one of multipleconditions in other rules) is that if it is determined that the user wasnot looking at the user device when the spoken user input was received,it can be determined that the user did not intend for the current spokenuser input to be directed at the virtual assistant.

In one example probabilistic system, a determination that the user waslooking at the user device when the spoken user input was received cancontribute a positive value to the final likelihood or confidence score,while a determination that the user was not looking at the user devicewhen the spoken user input was received can contribute a zero or anegative value to the final likelihood or confidence score. Themagnitude of the positive or negative contribution can be adjusted basedon the overall system design.

In yet other examples, the image data can be analyzed to determine anorientation of the device relative to the user. For example, the imagedata can be analyzed using known facial recognition techniques todetermine whether or not the user is positioned in front of the userdevice based on whether or not the user appears in the field of view ofoptical sensor 222. Similarly, the image data can be analyzed usingknown image recognition techniques to determine whether or not the useris performing a particular action (e.g., pointing at the user device,gesturing at the user device, or the like) or positioned in a predefinedway (e.g., sitting in front of a television, holding a remote, or thelike). In these examples, a determination that the user was in front ofthe user device, performing a particular action, or positioned in apredefined way when the spoken user input was received can be indicativethat the user was more likely to have intended for the current spokenuser input to be directed at the virtual assistant, while adetermination that the user was not in front of the user device, was notperforming a particular action, or was not positioned in a predefinedway when the spoken user input was received can be indicative that theuser was less likely to have intended for the current spoken user inputto be directed at the virtual assistant or can be neutral regarding thelikelihood that the user intended for the current spoken user input tobe directed at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if it is determined that the user was in front of theuser device, performing a particular action, or positioned in apredefined way when the spoken user input was received, then it can bedetermined that the user intended for the current spoken user input tobe directed at the virtual assistant. Another rule that can be used(alone, in combination with other rules, or as one of multipleconditions in other rules) is that if it is determined that the user wasnot in front of the user device, was not performing a particular action,or was not positioned in a predefined way when the spoken user input wasreceived, it can be determined that the user did not intend for thecurrent spoken user input to be directed at the virtual assistant.

In one example probabilistic system, a determination that the user wasin front of the user device, performing a particular action, orpositioned in a predefined way when the spoken user input was receivedcan contribute a positive value to the final likelihood or confidencescore, while a determination that the user was not in front of the userdevice, was not performing a particular action, or was not positioned ina predefined way when the spoken user input was received can contributea zero or a negative value to the final likelihood or confidence score.The magnitude of the positive or negative contribution can be adjustedbased on the overall system design.

In some examples, the contextual information can include orientationdata from motion sensor 210 of user device 102. Motion sensor 210 caninclude any type of orientation sensor, such as an inclinometer,compass, gyroscope, or the like, that is capable of generatingorientation data that represents a free-space orientation of the userdevice. In some examples, certain orientations of the user device (e.g.,the front of the device is facing up, the device is upright, the deviceis in an orientation in which a display of the device can be viewed bythe user, or the like) can be indicative that the user was more likelyto have intended for the current spoken user input to be directed at thevirtual assistant, while other orientations of the user device (e.g.,the front of the device is facing down, the device is upside down, thedevice is in an orientation in which a display of the device cannot beviewed by the user, or the like) can be indicative that the user wasless likely to have intended for the current spoken user input to bedirected at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the device was in one of a set of orientations (e.g.,the front of the device is facing up, the device is upright, the deviceis in an orientation in which a display of the device can be viewed bythe user, or the like) when the spoken user input was received, then itcan be determined that the user intended for the current spoken userinput to be directed at the virtual assistant. Another rule that can beused (alone, in combination with other rules, or as one of multipleconditions in other rules) is that if the device was not in one of theset of orientations when the spoken user input was received, it can bedetermined that the user did not intend for the current spoken userinput to be directed at the virtual assistant.

In one example probabilistic system, a determination that the userdevice is in one of a set of orientations (e.g., the front of the deviceis facing up, the device is upright, the device is in an orientation inwhich a display of the device can be viewed by the user, or the like)when the spoken user input was received can contribute a positive valueto the final likelihood or confidence score, while a determination thatuser device was not in one of the set of orientations when the spokenuser input was received can contribute a zero or a negative value to thefinal likelihood or confidence score. The magnitude of the positive ornegative contribution can be adjusted based on the overall systemdesign.

In some examples, the contextual information can include location datafrom a GPS receiver from other sensors 216 of user device 102. Thelocation data can represent a geographical location of the user device.In some examples, receiving a spoken user input while the user device isin certain locations (e.g., at home, in an office, or the like) can beindicative that the user was more likely to have intended for thecurrent spoken user input to be directed at the virtual assistant, whilereceiving the spoken user input while the user device is in certainother locations (e.g., at a movie theatre, in a conference room, or thelike) can be indicative that the user was less likely to have intendedfor the current spoken user input to be directed at the virtualassistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the device was located in one of a set of locations(e.g., at home, in an office, or the like) when the spoken user inputwas received, then it can be determined that the user intended for thecurrent spoken user input to be directed at the virtual assistant.Another rule that can be used (alone, in combination with other rules,or as one of multiple conditions in other rules) is that if the devicewas not located in one of the set of locations when the spoken userinput was received, it can be determined that the user did not intendfor the current spoken user input to be directed at the virtualassistant.

In one example probabilistic system, a determination that the userdevice was located in one of a set of locations (e.g., at home, in anoffice, or the like) when the spoken user input was received cancontribute a positive value to the final likelihood or confidence score,while a determination that the user device was not located in one of theset of locations when the spoken user input was received can contributea zero or a negative value to the final likelihood or confidence score.The magnitude of the positive or negative contribution can be adjustedbased on the overall system design.

In some examples, the contextual information can include operating statedata from memory 250 or another storage device located within or remotefrom user device 102. The operating state data can include anyinformation relating to the operating state of user device, such aswhether or not content is being displayed or otherwise being presentedto the user, a type or identification of the content being presented tothe user, an application being run by the user device, whether or not anotification has been recently presented to the user, a previous or mostrecent contact, a previous or most recent email, a previous or mostrecent SMS message, a previous or most recent phone call, calendarentries, reminders entries, webpage visits, on/off state of a display ofthe user device, whether or not the user device is receiving user inputother than the spoken user input, settings on the user device, previousactivity, or the like. In some examples, receiving the spoken user inputwhile the user device is in certain operating states (e.g., content orother information is being displayed to the user, content or otherinformation is being audibly presented to the user, a particular type ofcontent is being presented to the user, a particular content is beingpresented to the user, such as a conversation transcript between theuser and a virtual assistant, an application is being run by the userdevice, a notification has been recently presented to the user, thedisplay of the user device is on, the user device is receiving userinput other than the spoken user input, such as a mouse input, keyboardinput, touch sensitive display input, etc., an email was recentlysent/received to/from a contact or a particular contact, an SMS messagewas recently sent/received to/from a contact or a particular contact, aphone call was recently sent/received to/from a contact or a particularcontact, a particular setting is configured on the user device, aprevious activity was performed, or the like) can be indicative that theuser was more likely to have intended for the current spoken user inputto be directed at the virtual assistant, while receiving the spoken userinput while the user device is in certain other operating states (e.g.,content or other information is not being displayed to the user, contentor other information is not being audibly presented to the user, aparticular type of content is not being presented to the user, aparticular content is not being presented to the user, such as aconversation transcript between the user and a virtual assistant, anapplication is not being run by the user device, a notification has notbeen recently presented to the user, the display of the user device isoff, the user device is not receiving user input other than the spokenuser input, such as a mouse input, keyboard input, touch sensitivedisplay input, etc., an email was not recently sent/received to/from acontact or a particular contact, an SMS message was not recentlysent/received to/from a contact or a particular contact, a phone callwas not recently sent/received to/from a contact or a particularcontact, a particular setting is not configured on the user device, aprevious activity was not performed, or the like) can be indicative thatthe user was less likely to have intended for the current spoken userinput to be directed at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the display of the user device was on and the userdevice was presenting audio information to the user when the spoken userinput was received, then it can be determined that the user intended forthe current spoken user input to be directed at the virtual assistant.Another rule that can be used (alone, in combination with other rules,or as one of multiple conditions in other rules) is that if the displayof the user device was off and the user device was not presenting audioinformation to the user when the spoken user input was received, it canbe determined that the user did not intend for the current spoken userinput to be directed at the virtual assistant. Other types of operatingstate data can similarly be used to generate rules that cause adetermination to be made that the spoken user input was or was notintended for the virtual assistant.

In one example probabilistic system, a determination that the display ofthe user device was on and that the user device was presenting audioinformation to the user when the spoken user input was received cancontribute a positive value to the final likelihood or confidence score,while a determination that the display of the user device was off andthat the user device was not presenting audio information to the userwhen the spoken user input was received can contribute a zero or anegative value to the final likelihood or confidence score. Themagnitude of the positive or negative contribution can be adjusted basedon the overall system design. It should be appreciated that other typesof operating state data can be used in a similar manner to makepositive, negative, or neutral contributions to the final likelihood orconfidence score depending on whether or not the operating state dataindicates that the state of the device is one of a predetermined set ofstates.

In other examples, a semantic similarly analysis can be performed on thecurrent spoken user input and some or all of the operating state data.In these examples, a semantic distance between the current spoken userinput and one or more of the components of the operating state data canbe determined and used to determine whether or not the spoken user inputwas intend for the user device at block 308. In these examples, smallsemantic distance between the current spoken user input and one or morecomponents of the operating state data can be indicative that the userwas more likely to have intended for the current spoken user input to bedirected at the virtual assistant, while a large semantic distancebetween the current spoken user input and one or more components of theoperating state data can be indicative that the user was less likely tohave intended for the current spoken user input to be directed at thevirtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if a semantic distance between the current spoken userinput and one or more components of the operating state data (e.g., anapplication being run by the user device, a notification presented tothe user, a name in a contact list, a previous contact, a previousemail, a previous SMS message, content being presented to the user, acommand expected to be received from the user, such as requests fordirections while the user device is running a map application, contentnavigation instructions while the user device is in an eyes-free mode, a“start” instruction after previously receiving a “stop” or “pause”instruction, etc., or the like) is less than a threshold value, then itcan be determined that the user intended for the current spoken userinput to be directed at the virtual assistant. Another rule that can beused (alone, in combination with other rules, or as one of multipleconditions in other rules) is that if the semantic distance between thecurrent spoken user input and one or more components of the operatingstate data is greater than or equal to a threshold value, it can bedetermined that the user did not intend for the current spoken userinput to be directed at the virtual assistant.

In one example probabilistic system, a semantic distance between thecurrent spoken user input and one or more components of the operatingstate data can be used to calculate a positive, negative, or neutralcontribution to a final likelihood or confidence score, where the valueof the contribution can have a linear or non-linear relationship withthe semantic distance. For example, a semantic distance that is lessthan a threshold value can contribute a positive value to the finallikelihood or confidence score, where the magnitude of the positivevalue can be greater for smaller semantic distances. Similarly, asemantic distance that is greater than or equal to the threshold valuecan contribute a zero or negative value to the final likelihood orconfidence score, where the magnitude of the negative value can begreater for larger semantic distances.

In some examples, the contextual information can include lighting datafrom light sensor 212 of user device 102. The lighting data can includea representation of a brightness of ambient light received by lightsensor 212. In some examples, a higher brightness of the sensed ambientlight when the spoken user input was received can be indicative that theuser was more likely to have intended for the current spoken user inputto be directed at the virtual assistant (e.g., indicating that the useris in an environment in which speaking is acceptable), while a lowerbrightness of the sensed ambient light when the spoken user input wasreceived can be indicative that the user was less likely to haveintended for the current spoken user input to be directed at the virtualassistant (e.g., indicating that the user is in an environment in whichspeaking is not acceptable, such as a movie theatre). However, in otherexamples, a lower brightness of the sensed ambient light when the spokenuser input was received can be indicative that the user was more likelyto have intended for the current spoken user input to be directed at thevirtual assistant, while a higher brightness of the sensed ambient lightwhen the spoken user input was received can be indicative that the userwas less likely to have intended for the current spoken user input to bedirected at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the brightness of the sensed ambient light when thespoken user input was received is greater than a threshold brightness,then it can be determined that the user intended for the current spokenuser input to be directed at the virtual assistant. Another rule thatcan be used (alone, in combination with other rules, or as one ofmultiple conditions in other rules) is that if the brightness of thesensed ambient light when the spoken user input was received input isless than or equal to the threshold brightness, it can be determinedthat the user did not intend for the current spoken user input to bedirected at the virtual assistant.

In one example probabilistic system, the brightness of the sensedambient light when the spoken user input was received can be used tocalculate a positive, negative, or neutral contribution to a finallikelihood or confidence score, where the value of the contribution canhave a linear or non-linear relationship with the value of thebrightness of the sensed ambient light. For example, a brightness lessthan a threshold brightness can contribute a negative value to the finallikelihood or confidence score, where the magnitude of the negativevalue can be greater for lower brightness values. Similarly, abrightness greater than or equal to the threshold brightness cancontribute a zero or positive value to the final likelihood orconfidence score, where the magnitude of the negative value can begreater for higher brightness values.

In some examples, the contextual information can include speechrecognition data from an automatic speech recognition (ASR) enginelocated within or remote from user device 102 (e.g., from server system110). The speech recognition data can include an indication of whetheror not the ASR engine was able to recognize the spoken user input and/oris capable of responding to the spoken user input. In some examples, anindication that the ASR engine was able to recognize the spoken userinput and/or is capable of responding to the spoken user input can beindicative that the user was more likely to have intended for thecurrent spoken user input to be directed at the virtual assistant, whilean indication that the ASR engine was not able to recognize the spokenuser input and/or is not capable of responding to the spoken user inputcan be indicative that the user was less likely to have intended for thecurrent spoken user input to be directed at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the ASR engine was able to recognize the spoken userinput and/or is capable of responding to the spoken user input, then itcan be determined that the user intended for the current spoken userinput to be directed at the virtual assistant. Another rule that can beused (alone, in combination with other rules, or as one of multipleconditions in other rules) is that if the ASR engine was not able torecognize the spoken user input and/or is not capable of responding tothe spoken user input, it can be determined that the user did not intendfor the current spoken user input to be directed at the virtualassistant.

In one example probabilistic system, a determination that the ASR enginewas able to recognize the spoken user input and/or is capable ofresponding to the spoken user input can contribute a positive value tothe final likelihood or confidence score, while a determination that theASR engine was not able to recognize the spoken user input and/or is notcapable of responding to the spoken user input can contribute a zero ora negative value to the final likelihood or confidence score. Themagnitude of the positive or negative contribution can be adjusted basedon the overall system design.

In other examples, the speech recognition data from the ASR engine canfurther include an indication of the length (e.g., number of words,duration of speech, or the like) of the spoken user input. Generally, insome examples, a shorter length of the spoken user input can beindicative that the user was more likely to have intended for thecurrent spoken user input to be directed at the virtual assistant, whilea longer length of the spoken user input can be indicative that the userwas less likely to have intended for the current spoken user input to bedirected at the virtual assistant. However, in some examples, a longerlength of the spoken user input can be indicative that the user was morelikely to have intended for the current spoken user input to be directedat the virtual assistant, while a shorter length of the spoken userinput can be indicative that the user was less likely to have intendedfor the current spoken user input to be directed at the virtualassistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the length of the spoken user input is less than athreshold length, then it can be determined that the user intended forthe current spoken user input to be directed at the virtual assistant.Another rule that can be used (alone, in combination with other rules,or as one of multiple conditions in other rules) is that if the lengthof the spoken user input is greater than or equal to the thresholdlength, it can be determined that the user did not intend for thecurrent spoken user input to be directed at the virtual assistant.

In one example probabilistic system, the length of the spoken user inputcan be used to calculate a positive, negative, or neutral contributionto a final likelihood or confidence score, where the value of thecontribution can have a linear or non-linear relationship with the valueof the length of the spoken user input. For example, a length less thana threshold length can contribute a positive value to the finallikelihood or confidence score, where the magnitude of the positivevalue can be greater for shorter lengths. Similarly, a length greaterthan or equal to the threshold distance can contribute a zero ornegative value to the final likelihood or confidence score, where themagnitude of the negative value can be greater for longer lengths.

In other examples, the speech recognition data from the ASR engine canfurther include noun or pronouns identified from within the spoken userinput. For example, the speech recognition data can include noun orpronouns, such as “honey,” “he,” “she,” or the first or last name of aperson. Generally, in some examples, the presence of one of these nounsor pronouns can be indicative that the user was less likely to haveintended for the current spoken user input to be directed at the virtualassistant, while the absence of one of these nouns or pronouns (orpresence of non-human identifiers, such as “Siri”) can be indicativethat the user was more likely to have intended for the current spokenuser input to be directed at the virtual assistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the spoken user input includes one of a set of nounsor pronouns, then it can be determined that the user did not intend forthe current spoken user input to be directed at the virtual assistant.Another rule that can be used (alone, in combination with other rules,or as one of multiple conditions in other rules) is that if the spokenuser input does not include one of the set of nouns or pronouns (orincludes one of another set of nouns or pronouns), it can be determinedthat the user intended for the current spoken user input to be directedat the virtual assistant.

In one example probabilistic system, a determination that the spokenuser input includes one of a set of nouns or pronouns can contribute anegative value to the final likelihood or confidence score, while adetermination that the spoken user input does not include one of the setof nouns or pronouns (or includes one of another set of nouns orpronouns) can contribute a positive or zero value to the finallikelihood or confidence score. The magnitude of the positive ornegative contribution can be adjusted based on the overall systemdesign.

In some examples, the contextual information can include user data frommemory 250 or another storage device located within or remote from userdevice 102. The user data can include any type of information associatedwith the user, such as a contact list, calendar, preferences, personalinformation, financial information, family information, or the like. Insome examples, the user data can be compared with other types ofcontextual information at block 308 to assist in the determination ofwhether or not the spoken user input was intend for the virtualassistant. For example, the time that the spoken user input was receivedcan be compared with the user's calendar to determine if the user was atan event in which the user was more or less likely to be conversing withthe virtual assistant of the user device, the speech recognition datafrom the ASR engine can be compared with contacts in the user's contactlist to determine if the a name from the user's contact list wasmentioned in the spoken user input, the speech recognition data from theASR engine can be compared with user preferences to determine if thespoken user input corresponds to a previously defined phrase that shouldor should not be ignored by the virtual assistant, or the like.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the current spoken user input was received at a timewithin a predetermined set of times (e.g., when the user's calendarindicates that the user was in a meeting or otherwise engaged in anactivity deemed to be one in which the user would not converse with avirtual assistant), then it can be determined that the user did notintend for the current spoken user input to be directed at the virtualassistant. Another rule that can be used (alone, in combination withother rules, or as one of multiple conditions in other rules) is that ifthe current spoken user input was received at a time outside thepredetermined set of times (e.g., when the user's calendar indicatesthat the user was not in a meeting or otherwise engaged in an activitydeemed to be one in which the user would not converse with a virtualassistant), it can be determined that the user intended for the currentspoken user input to be directed at the virtual assistant. Other typesof user data can similarly be used to generate rules that cause adetermination to be made that the spoken user input was or was notintended for the virtual assistant.

In one example probabilistic system, a determination that the currentspoken user input was received at a time that the user's calendarindicates that the user was in a meeting or otherwise engaged in anactivity deemed to be one in which the user would not converse with avirtual assistant can contribute a negative or zero value to the finallikelihood or confidence score, while a determination that the currentspoken user input was received at a time that the user's calendarindicates that the user was not in a meeting or otherwise engaged in anactivity deemed to be one in which the user would not converse with avirtual assistant can contribute a positive value to the finallikelihood or confidence score. The magnitude of the positive ornegative contribution can be adjusted based on the overall systemdesign. It should be appreciated that other types of user data can beused in a similar manner to make positive, negative, or neutralcontributions to the final likelihood or confidence score.

In some examples, the contextual information can include motion datafrom motion sensor 210 or an accelerometer of other sensors 216 of userdevice 102. The motion data can represent movement of the user deviceand can be used to detect movement of the device caused by the usershaking the device, movement of the device toward or away from the user(e.g., movement toward or away from the user's mouth), movement causedby the user wearing the device (e.g., as a watch or other wearabledevice), or the like. In some examples, certain motions experienced bythe user device (e.g., shaking, movement associated with the user devicebeing worn by the user, movement toward the user, etc.) can beindicative that the user was more likely to have intended for thecurrent spoken user input to be directed at the virtual assistant, whileother motions experienced by the user device (e.g., movement away fromthe user) can be indicative that the user was less likely to haveintended for the current spoken user input to be directed at the virtualassistant.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the motion data indicates that the user device wasmoved toward the user's mouth before the spoken user input was received,then it can be determined that the user intended for the current spokenuser input to be directed at the virtual assistant. Another rule thatcan be used (alone, in combination with other rules, or as one ofmultiple conditions in other rules) is that if the motion data indicatesthat the device was not moved toward the user's mouth before the spokenuser input was received, it can be determined that the user did notintend for the current spoken user input to be directed at the virtualassistant. Other movements can similarly be used to generate rules thatcause a determination to be made that the spoken user input was or wasnot intended for the virtual assistant.

In one example probabilistic system, a determination that the userdevice was moved in one of a predetermined set of movements (e.g.,toward the user's mouth before the spoken user input was received) cancontribute a positive value to the final likelihood or confidence score,while a determination that user device was not moved in one of apredetermined set of movements can contribute a zero or a negative valueto the final likelihood or confidence score. The magnitude of thepositive or negative contribution can be adjusted based on the overallsystem design. It should be appreciated that other movements can be usedin a similar manner to make positive, negative, or neutral contributionsto the final likelihood or confidence score.

In some examples, the contextual information can include temperaturedata from a temperature sensor of other sensors 216 of user device 102.The temperature data can represent a temperature sensed by thetemperature sensor and can be used to determine whether or not the userdevice is being held by the user. For example, a higher temperature or atemperature in a particular range can suggest that the device is beingheld in the hand of a user, while a lower temperature or a temperatureoutside the particular range can suggest that the device is not beingheld by the user.

In one example rule-based system, one rule that can be used (alone, incombination with other rules, or as one of multiple conditions in otherrules) is that if the temperature is within a particular range oftemperatures corresponding to the user device being held by a user, thenit can be determined that the user intended for the current spoken userinput to be directed at the virtual assistant. Another rule that can beused (alone, in combination with other rules, or as one of multipleconditions in other rules) is that if the temperature is not within aparticular range of temperatures corresponding to the user device beingheld by a user, it can be determined that the user did not intend forthe current spoken user input to be directed at the virtual assistant.

In one example probabilistic system, a determination, based on thetemperature data, that the user device was being held by the user whenthe spoken user input was received can contribute a positive value tothe final likelihood or confidence score, while a determination, basedon the temperature data, that the user device was not being held by theuser when the spoken user input was received can contribute a zero or anegative value to the final likelihood or confidence score. Themagnitude of the positive or negative contribution can be adjusted basedon the overall system design.

Electronic Device

In accordance with some examples, FIG. 5 shows a functional blockdiagram of an electronic device 500 configured in accordance with theprinciples of the various described examples. The functional blocks ofthe device can be implemented by hardware, software, or a combination ofhardware and software to carry out the principles of the variousdescribed examples. It is understood by persons of skill in the art thatthe functional blocks described in FIG. 5 can be combined or separatedinto sub-blocks to implement the principles of the various describedexamples. Therefore, the description herein optionally supports anypossible combination or separation or further definition of thefunctional blocks described herein.

As shown in FIG. 5, electronic device 500 can include a touch screendisplay unit 502 configured to display a user interface and to receivetouch input, and a sound receiving unit 504 configured to receive soundinput. In some examples, electronic device 500 can include a speakerunit 506 configured to generate sound. Electronic device 500 can furtherinclude a processing unit 508 coupled to touch screen display unit 502and sound receiving unit 504 (and, optionally, coupled to speaker unit506). In some examples, processing unit 508 can include a firstmonitoring unit 510, a speech identifying unit 512, a responsedetermination unit 514, a response generating unit 516, a secondmonitoring unit 518, and a third monitoring unit 520.

Processing unit 508 can be configured to receive an audio input (e.g.,from audio receiving unit 504). Processing unit 508 can be configured tomonitor the audio input (e.g., using first monitoring unit 510) toidentify a first spoken user input in the audio input. Upon identifyingthe first spoken user input in the audio input, processing unit 508 canbe configured to determine (e.g., using response determination unit514), based on contextual information associated with the first spokenuser input, whether a response to the first spoken user input should begenerated. In response to determining that a response should begenerated, processing unit 508 can be configured to generate a response(e.g., using response generating unit 516) to the first spoken userinput and to again monitor the received audio input for a second spokenuser request (e.g., using second monitoring unit 518). In response todetermining that a response should not be generated, processing unit 508can be configured to again monitor the received audio input for a secondspoken user request (e.g., using second monitoring unit 518) withoutgenerating a response to the first spoken user input.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input without identifying one or more predeterminedwords at the start of the first spoken user input. In other examples,processing unit 508 can be configured to determine (e.g., using responsedetermination unit 514) whether to respond to the first spoken userinput without identifying a physical or virtual button input receivedprior to receiving the first spoken user input.

In some examples, processing unit 508 can be configured to generate aresponse (e.g., using response generating unit 516) to the first spokenuser input by performing speech-to-text conversion on the first spokenuser input, determining a user intent based on the first spoken userinput, determining a task to be performed based on the first spoken userinput, determining a parameter for the task to be performed based on thefirst spoken user input, performing the task to be performed, displayinga text response to the first spoken user input, or outputting an audioresponse to the first spoken user input.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by evaluating one or more conditional rules thatdepend on the contextual information associated with the first spokenuser input.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based onthe contextual information associated with the first spoken user inputand comparing the likelihood score to a threshold value.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input based on contextual information associated withthe first spoken user input that includes one or more of an elapsed timebetween receiving the first spoken user input and a previous user input,a previous spoken user input, a distance between a user and theelectronic device when the first spoken user input was received, anorientation of the electronic device when the first spoken user inputwas received, an orientation between the user and the electronic devicewhen the first spoken user input was received, a direction of the user'seyes when the first spoken user input was received, an indication ofwhether the first spoken user input was recognized by an automaticspeech recognizer, a semantic relationship between the first spoken userinput and the previous spoken user input, a length of the first spokenuser input, an identification of a speaker of the first spoken userinput, a time the first spoken user input was received, an indication ofwhether the electronic device was outputting information to the userwhen the first spoken user input was received, an expectation ofreceiving input from the user, an indication of whether the electronicdevice was being held when the first spoken user input was received, anoperating state of the electronic device when the first spoken userinput was received, a previous action performed by the electronicdevice, an indication of whether content was being displayed by theelectronic device when the first spoken user input was received, asemantic relationship between the first spoken user input and thecontent being displayed by the electronic device when the first spokenuser input was received, a position of the user when the first spokenuser input was received, a gesture being performed by the user when thefirst spoken user input was received, a previous output of theelectronic device, a location of the electronic device when the firstspoken user input was received, an application being run by theelectronic device when the first spoken user input was received, aprevious contact, a previous email, a previous SMS message, a movementof the electronic device when the first spoken user input was received,a user setting of the electronic device, an amount of light sensed bythe electronic device when the first spoken user input was received, andcalendar data.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an elapsed time between receivingthe first spoken user input and a previous user input. In theseexamples, calculating the likelihood score can include decreasing thelikelihood score in response to a value of the elapsed time beinggreater than a threshold duration and increasing the likelihood score inresponse to the value of the elapsed time being less than the thresholdduration. In some examples, the previous user input can include apreviously received touch input on a touch sensitive display, a mouseclick, a button press, or a spoken user input.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a previous spoken user input. Inthese examples, calculating the likelihood score can include increasingthe likelihood score in response to detecting a match between theprevious spoken user input and the first spoken user input.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a distance between a user and theelectronic device when the first spoken user input was received. Inthese examples, calculating the likelihood score can include decreasingthe likelihood score in response to the distance being greater than athreshold distance and increasing the likelihood score in response tothe distance being less than the threshold distance. In some examples,the distance can be determined based at least in part on a volume of thefirst spoken user input, a distance measured by a proximity sensor, animage generated by an image sensor, or accelerometer data from anaccelerometer.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an orientation of the electronicdevice when the first spoken user input was received. In these examples,calculating the likelihood score can include decreasing the likelihoodscore in response to the orientation of the device being facedown orupside down and increasing the likelihood score in response to theorientation of the device being face up or upright.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an orientation between the user andthe electronic device when the first spoken user input was received. Inthese examples, calculating the likelihood score can include increasingthe likelihood score in response to the orientation being one in which adisplay of the electronic device is oriented towards the user anddecreasing the likelihood score in response to the orientation being onein which the display of the electronic device is oriented away from theuser.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a direction of the user's eyes whenthe first spoken user input was received. In these examples, calculatingthe likelihood score can include increasing the likelihood score inresponse to the direction of the user's eyes being pointed at theelectronic device and decreasing the likelihood score in response to thedirection of the user's eyes being pointed away from the electronicdevice.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an indication of whether the firstspoken user input was recognized by an automatic speech recognizer. Inthese examples, calculating the likelihood score can include increasingthe likelihood score in response to the indication indicating that thefirst spoken user input was recognized by the automatic speechrecognizer and decreasing the likelihood score in response to theindication indicating that the first spoken user input was notrecognized by the automatic speech recognizer.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a semantic relationship between thefirst spoken user input and the previous spoken user input. In theseexamples, calculating the likelihood score can include increasing thelikelihood score in response to a value of the semantic relationshipbeing greater than a spoken user input semantic threshold value anddecreasing the likelihood score in response to the value of the semanticrelationship being less than the spoken user input semantic thresholdvalue.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a length of the first spoken userinput. In these examples, calculating the likelihood score can includeincreasing the likelihood score in response to the length of the firstspoken user input less than a threshold length and decreasing thelikelihood score in response to the length of the first spoken userinput being greater than the threshold length.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an identification of a speaker ofthe first spoken user input. In some examples, calculating thelikelihood score can include increasing the likelihood score in responseto the identification of the speaker of the first spoken user inputbeing one of a list of known or authorized speakers and decreasing thelikelihood score in response to the identification of the speaker of thefirst spoken user input not being one of a list of known or authorizedspeakers. In other examples, calculating the likelihood score caninclude increasing the likelihood score in response to theidentification of the speaker of the first spoken user input being thesame as an identification of a speaker of the previous spoken user inputand decreasing the likelihood score in response to the identification ofthe speaker of the first spoken user input being different than theidentification of the speaker of the previous spoken user input.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a time the first spoken user inputwas received. In these examples, calculating the likelihood score caninclude increasing the likelihood score in response to the time beingwithin a predetermined set of times and decreasing the likelihood scorein response to the time not being within the predetermined set of times.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an indication of whether theelectronic device was outputting information to the user when the firstspoken user input was received. In these examples, calculating thelikelihood score can include increasing the likelihood score in responseto the indication indicating that the electronic device was outputtinginformation to the user when the first spoken user input was receivedand decreasing the likelihood score in response to the indicationindicating that the electronic device was not outputting information tothe user when the first spoken user input was received.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an expectation of receiving inputfrom the user. In these examples, calculating the likelihood score caninclude increasing the likelihood score in response to the expectationof receiving input from the user indicating that input was expected tobe received from the user and decreasing the likelihood score inresponse to the expectation of receiving input from the user indicatingthat input was not expected to be received from the user.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an indication of whether theelectronic device is being held when the first spoken user input wasreceived. In these examples, calculating the likelihood score caninclude increasing the likelihood score in response to the indicationindicating that the electronic device was being held when the firstspoken user input was received and decreasing the likelihood score inresponse to the indication indicating that the electronic device was notbeing held when the first spoken user input was received.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an operating state of theelectronic device when the first spoken user input was received. Inthese examples, calculating the likelihood score can include increasingthe likelihood score in response to the operating state of theelectronic device being one of a set of predetermined operating statesand decreasing the likelihood score in response to the operating stateof the electronic device not being one of the set of predeterminedoperating states.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a previous action performed by theelectronic device. In these examples, calculating the likelihood scorecan include increasing the likelihood score in response to the previousaction performed by the electronic device being one of a set ofpredetermined actions and decreasing the likelihood score in response tothe previous action performed by the electronic device not being one ofthe set of predetermined actions.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an indication of whether thecontent was being displayed by the electronic device when the firstspoken user input was received. In these examples, calculating thelikelihood score can include increasing the likelihood score in responseto the indication indicating that content was being displayed by theelectronic device when the first spoken user input was received.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a semantic relationship between thefirst spoken user input and content being displayed by the electronicdevice when the first spoken user input was received. In these examples,calculating the likelihood score can include increasing the likelihoodscore in response to a value of the semantic relationship being greaterthan a content semantic threshold value and decreasing the likelihoodscore in response to the value of the semantic relationship being lessthan the content semantic threshold value.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a position of the user when thefirst spoken user input was received. In these examples, calculating thelikelihood score can include increasing the likelihood score in responseto the position of the user being one of a predetermined set ofpositions and decreasing the likelihood score in response to theposition of the user not being one of the predetermined set ofpositions.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a gesture being performed by theuser when the first spoken user input was received. In these examples,calculating the likelihood score can include increasing the likelihoodscore in response to the gesture being one of a predetermined set ofgestures and decreasing the likelihood score in response to the gesturenot being one of the predetermined set of gestures.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a semantic relationship between thefirst spoken user input and the previous output of the electronicdevice. In these examples, calculating the likelihood score can includeincreasing the likelihood score in response to a value of the semanticrelationship being greater than a previous output semantic thresholdvalue and decreasing the likelihood score in response to the value ofthe semantic relationship being less than the previous output semanticthreshold value.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a location of the electronic devicewhen the first spoken user input was received. In these examples,calculating the likelihood score can include decreasing the likelihoodscore in response to the location being one of a predetermined set oflocations and increasing the likelihood score in response to thelocation not being one of the predetermined set of locations.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a semantic relationship between thefirst spoken user input an application being run by the electronicdevice when the first spoken user input was received. In these examples,calculating the likelihood score can include increasing the likelihoodscore in response to a value of the semantic relationship being greaterthan an application semantic threshold value and decreasing thelikelihood score in response to the value of the semantic relationshipbeing less than the application semantic threshold value.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a semantic relationship between thefirst spoken user input and a previous contact. In these examples,calculating the likelihood score can include increasing the likelihoodscore in response to a value of the semantic relationship being greaterthan a previous contact semantic threshold value and decreasing thelikelihood score in response to the value of the semantic relationshipbeing less than the previous contact semantic threshold value.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a semantic relationship between thefirst spoken user input and a previous email. In these examples,calculating the likelihood score can include increasing the likelihoodscore in response to a value of the semantic relationship being greaterthan a previous email semantic threshold value and decreasing thelikelihood score in response to the value of the semantic relationshipbeing less than the previous email semantic threshold value.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a semantic relationship between thefirst spoken user input and a previous SMS message. In these examples,calculating the likelihood score can include increasing the likelihoodscore in response to a value of the semantic relationship being greaterthan a previous SMS message semantic threshold value and decreasing thelikelihood score in response to the value of the semantic relationshipbeing less than the previous SMS semantic threshold value.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a movement of the electronicdevice. In these examples, calculating the likelihood score can includeincreasing the likelihood score in response to the movement being one ofa predetermined set of movements and decreasing the likelihood score inresponse to the movement not being one of the predetermined set ofmovements.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes a user setting. In these examples,calculating the likelihood score can include increasing the likelihoodscore in response to the user setting being one of a predetermined setof user settings and decreasing the likelihood score in response to theuser setting not being one of the predetermined set of user settings.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes an amount of light sensed by theelectronic device. In these examples, calculating the likelihood scorecan include increasing the likelihood score in response to the amount oflight being greater than a threshold amount of light and decreasing thelikelihood score in response to the amount of light being less than thethreshold amount of light.

In some examples, processing unit 508 can be configured to determine(e.g., using response determination unit 514) whether to respond to thefirst spoken user input by calculating a likelihood score that thevirtual assistant should respond to the first spoken user input based oncontextual information that includes calendar data. In these examples,calculating the likelihood score can include decreasing the likelihoodscore in response to the calendar data indicating that the user isoccupied at the time that the first spoken user input was received.

Processing unit 508 can be further configured to monitor the audio input(e.g., using second monitoring unit 518) to identify a second spokenuser input in the audio input. Upon identifying the second spoken userinput in the audio input, processing unit 508 can be configured todetermine (e.g., using response determination unit 514), based oncontextual information associated with the second spoken user input,whether a response to the second spoken user input should be generated.In response to determining that a response should be generated,processing unit 508 can be configured to generate a response (e.g.,using response generating unit 516) to the second spoken user input andto again monitor the received audio input for a third spoken userrequest (e.g., using third monitoring unit 520). In response todetermining that a response should not be generated, processing unit 508can be configured to again monitor the received audio input for thethird spoken user request (e.g., using third monitoring unit 520)without generating a response to the second spoken user input.

As described above, one aspect of the present technology is thegathering and use of data available from various sources to improve thedelivery to users of invitational content or any other content that maybe of interest to them. The present disclosure contemplates that in someinstances, this gathered data can include personal information data thatuniquely identifies or can be used to contact or locate a specificperson. Such personal information data can include demographic data,location-based data, telephone numbers, email addresses, home addresses,or any other identifying information.

The present disclosure recognizes that the use of such personalinformation data, in the present technology, can be used to the benefitof users. For example, the personal information data can be used todeliver targeted content that is of greater interest to the user.Accordingly, use of such personal information data enables calculatedcontrol of the delivered content. Further, other uses for personalinformation data that benefit the user are also contemplated by thepresent disclosure.

The present disclosure further contemplates that the entitiesresponsible for the collection, analysis, disclosure, transfer, storage,or other use of such personal information data will comply withwell-established privacy policies and/or privacy practices. Inparticular, such entities should implement and consistently use privacypolicies and practices that are generally recognized as meeting orexceeding industry or governmental requirements for maintaining personalinformation data private and secure. For example, personal informationfrom users should be collected for legitimate and reasonable uses of theentity and not shared or sold outside of those legitimate uses. Further,such collection should occur only after receiving the informed consentof the users. Additionally, such entities would take any needed stepsfor safeguarding and securing access to such personal information dataand ensuring that others with access to the personal information dataadhere to their privacy policies and procedures. Further, such entitiescan subject themselves to evaluation by third parties to certify theiradherence to widely accepted privacy policies and practices.

Despite the foregoing, the present disclosure also contemplates examplesin which users selectively block the use of, or access to, personalinformation data. That is, the present disclosure contemplates thathardware and/or software elements can be provided to prevent or blockaccess to such personal information data. For example, in the case ofadvertisement delivery services, the present technology can beconfigured to allow users to select to “opt in” or “opt out” ofparticipation in the collection of personal information data duringregistration for services. In another example, users can select not toprovide location information for targeted content delivery services. Inyet another example, users can select to not provide precise locationinformation, but permit the transfer of location zone information.

Therefore, although the present disclosure broadly covers use ofpersonal information data to implement one or more various disclosedexamples, the present disclosure also contemplates that the variousexamples can also be implemented without the need for accessing suchpersonal information data. That is, the various examples of the presenttechnology are not rendered inoperable due to the lack of all or aportion of such personal information data. For example, content can beselected and delivered to users by inferring preferences based onnon-personal information data or a bare minimum amount of personalinformation, such as the content being requested by the deviceassociated with a user, other non-personal information available to thecontent delivery services, or publicly available information.

Although examples have been fully described with reference to theaccompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art. Suchchanges and modifications are to be understood as being included withinthe scope of the various examples as defined by the appended claims.

What is claimed is:
 1. A non-transitory computer-readable storage mediumstoring one or more programs, the one or more programs comprisinginstructions, which when executed by one or more processors of anelectronic device, cause the electronic device to: receive a firstspoken input, wherein the first spoken input comprises a spoken triggerand requests performance of a first task; in accordance with adetermination that the first spoken input comprises the spoken trigger;activate a virtual assistant operating on the electronic device;perform, by the activated virtual assistant, the first task based on thefirst spoken input; and provide, at a first time, a first responseindicating the performance of the first task, wherein providing thefirst response includes providing at least one of audio output anddisplayed output; within a predetermined duration from the first time:monitor received audio input to identify a second spoken input in theaudio input, wherein the second spoken input does not comprise thespoken trigger; in accordance with identifying the second spoken input,perform a second task based on the second spoken input; and provide asecond response indicating the performance of the second task.
 2. Thenon-transitory computer-readable storage medium of claim 1, wherein theone or more programs further comprise instructions, which when executedby the one or more processors, cause the electronic device to: whilemonitoring the received audio input, output a visual indicator, thevisual indicator indicating that the electronic device is capable ofresponding to received spoken input not including the spoken trigger. 3.The non-transitory computer-readable storage medium of claim 1, whereinthe second spoken input is identified without identifying a physical orvirtual button input received prior to identifying the second spokeninput.
 4. The non-transitory computer-readable storage medium of claim1, wherein the one or more programs further comprise instructions, whichwhen executed by the one or more processors, cause the electronic deviceto: after the predetermined duration from the first time: cease tomonitor for spoken input in the received audio input; and receive athird spoken input, wherein the third spoken input comprises the spokentrigger; and in accordance with a determination that the third spokeninput comprises the spoken trigger, perform a third task based on thethird spoken input.
 5. The non-transitory computer-readable storagemedium of claim 1, wherein the one or more programs further compriseinstructions, which when executed by the one or more processors, causethe electronic device to: prior to performing the second task, determinewhether to respond to the second spoken input based on contextualinformation associated with the second spoken input.
 6. Thenon-transitory computer-readable storage medium of claim 5, whereindetermining whether to respond to the second spoken input includesevaluating one or more conditional rules that depend on the contextualinformation.
 7. The non-transitory computer-readable storage medium ofclaim 5, wherein determining whether to respond to the second spokeninput includes: calculating a likelihood score that a virtual assistantshould provide the second response to the second spoken input based onthe contextual information.
 8. The non-transitory computer-readablestorage medium of claim 7, wherein the contextual information comprisesan elapsed time between receiving the second spoken input and the firstspoken input, and wherein calculating the likelihood score that thevirtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: decreasingthe likelihood score in response to a value of the elapsed time beinggreater than a threshold duration; and increasing the likelihood scorein response to the value of the elapsed time being less than thethreshold duration.
 9. The non-transitory computer-readable storagemedium of claim 7, wherein the contextual information comprises thefirst spoken input, and wherein calculating the likelihood score thatthe virtual assistant should provide the second response to the secondspoken input based on the contextual information comprises increasingthe likelihood score in response to detecting a match between the firstspoken input and the second spoken input.
 10. The non-transitorycomputer-readable storage medium of claim 7, wherein the contextualinformation comprises an orientation of the electronic device when thesecond spoken input was received, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:decreasing the likelihood score in response to the orientation of thedevice being face down or upside down; and increasing the likelihoodscore in response to the orientation of the device being face up orupright.
 11. The non-transitory computer-readable storage medium ofclaim 7, wherein the contextual information comprises an orientationbetween a user and the electronic device when the second spoken inputwas received, and wherein calculating the likelihood score that thevirtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: increasingthe likelihood score in response to the orientation being one in which adisplay of the electronic device is oriented towards the user; anddecreasing the likelihood score in response to the orientation being onein which the display of the electronic device is oriented away from theuser.
 12. The non-transitory computer-readable storage medium of claim7, wherein the contextual information comprises an indication of whetherthe second spoken input was recognized by an automatic speechrecognizer, and wherein calculating the likelihood score that thevirtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: increasingthe likelihood score in response to the indication indicating that thesecond spoken input was recognized by the automatic speech recognizer;and decreasing the likelihood score in response to the indicationindicating that the second spoken input was not recognized by theautomatic speech recognizer.
 13. The non-transitory computer-readablestorage medium of claim 7, wherein the contextual information comprisesa semantic relationship between the second spoken input and the firstspoken input, and wherein calculating the likelihood score that thevirtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: increasingthe likelihood score in response to a value of the semantic relationshipbeing greater than a spoken user input semantic threshold value; anddecreasing the likelihood score in response to the value of the semanticrelationship being less than the spoken user input semantic thresholdvalue.
 14. The non-transitory computer-readable storage medium of claim7, wherein the contextual information comprises an identification of aspeaker of the second spoken input, and wherein calculating thelikelihood score that the virtual assistant should provide the secondresponse to the second spoken input based on the contextual informationcomprises: increasing the likelihood score in response to the identifiedspeaker being included in a list of authorized speakers; and decreasingthe likelihood score in response to the identified speaker not beingincluded in the list of authorized speakers.
 15. The non-transitorycomputer-readable storage medium of claim 7, wherein the contextualinformation comprises an indication of whether the electronic device wasoutputting information to a user when the second spoken input wasreceived, and wherein calculating the likelihood score that the virtualassistant should provide the second response to the second spoken inputbased on the contextual information comprises: increasing the likelihoodscore in response to the indication indicating that the electronicdevice was outputting information to the user when the second spokeninput was received; and decreasing the likelihood score in response tothe indication indicating that the electronic device was not outputtinginformation to the user when the second spoken input was received. 16.The non-transitory computer-readable storage medium of claim 7, whereinthe contextual information comprises an indication of whether theelectronic device is being held when the second spoken input wasreceived, and wherein calculating the likelihood score that the virtualassistant should provide the second response to the second spoken inputbased on the contextual information comprises: increasing the likelihoodscore in response to the indication indicating that the electronicdevice was being held when the second spoken input was received; anddecreasing the likelihood score in response to the indication indicatingthat the electronic device was not being held when the second spokeninput was received.
 17. The non-transitory computer-readable storagemedium of claim 7, wherein the contextual information comprises aprevious action performed by the electronic device, and whereincalculating the likelihood score that the virtual assistant shouldprovide the second response to the second spoken input based on thecontextual information comprises: increasing the likelihood score inresponse to the previous action performed by the electronic device beingone of a set of predetermined actions; and decreasing the likelihoodscore in response to the previous action performed by the electronicdevice not being one of the set of predetermined actions.
 18. Thenon-transitory computer-readable storage medium of claim 7, wherein thecontextual information comprises an indication of whether content wasbeing displayed by the electronic device when the second spoken inputwas received, and wherein calculating the likelihood score that thevirtual assistant should provide the second response to the secondspoken input based on the contextual information comprises increasingthe likelihood score in response to the indication indicating thatcontent was being displayed by the electronic device when the secondspoken input was received.
 19. The non-transitory computer-readablestorage medium of claim 7, wherein the contextual information comprisesa semantic relationship between the second spoken input and contentbeing displayed by the electronic device when the second spoken inputwas received, and wherein calculating the likelihood score that thevirtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: increasingthe likelihood score in response to a value of the semantic relationshipbeing greater than a content semantic threshold value; and decreasingthe likelihood score in response to the value of the semanticrelationship being less than the content semantic threshold value. 20.The non-transitory computer-readable storage medium of claim 7, whereinthe contextual information comprises a position of a user when thesecond spoken input was received, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:increasing the likelihood score in response to the position of the userbeing one of a predetermined set of positions; and decreasing thelikelihood score in response to the position of the user not being oneof the predetermined set of positions.
 21. The non-transitorycomputer-readable storage medium of claim 7, wherein the contextualinformation comprises a semantic relationship between the second spokeninput and the first response, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:increasing the likelihood score in response to a value of the semanticrelationship being greater than a semantic threshold value; anddecreasing the likelihood score in response to the value of the semanticrelationship being less than the semantic threshold value.
 22. Thenon-transitory computer-readable storage medium of claim 7, wherein thecontextual information comprises a semantic relationship between thesecond spoken input and an application being run by the electronicdevice when the second spoken input was received, and whereincalculating the likelihood score that the virtual assistant shouldprovide the second response to the second spoken input based on thecontextual information comprises: increasing the likelihood score inresponse to a value of the semantic relationship being greater than anapplication semantic threshold value; and decreasing the likelihoodscore in response to the value of the semantic relationship being lessthan the application semantic threshold value.
 23. The non-transitorycomputer-readable storage medium of claim 7, wherein the contextualinformation comprises a movement of the electronic device, and whereincalculating the likelihood score that the virtual assistant shouldprovide the second response to the second spoken input based on thecontextual information comprises: increasing the likelihood score inresponse to the movement being one of a predetermined set of movements;and decreasing the likelihood score in response to the movement notbeing one of the predetermined set of movements.
 24. The non-transitorycomputer-readable storage medium of claim 7, wherein the contextualinformation comprises a direction of a user's gaze when the secondspoken input was received, and wherein calculating the likelihood scorethat the virtual assistant should provide the second response to thesecond spoken input based on the contextual information comprises:increasing the likelihood score in response to the direction of theuser's gaze being pointed at the electronic device when the secondspoken input was received; and decreasing the likelihood score inresponse to the direction of the user's gaze being pointed away from theelectronic device when the second spoken input was received.
 25. Amethod, comprising: at an electronic device with one or more processorsand memory: receiving a first spoken input, wherein the first spokeninput comprises a spoken trigger and requests performance of a firsttask; in accordance with a determination that the first spoken inputcomprises the spoken trigger; activating a virtual assistant operatingon the electronic device; performing, by the activated virtualassistant, the first task based on the first spoken input; andproviding, at a first time, a first response indicating the performanceof the first task, wherein providing the first response includesproviding at least one of audio output and displayed output; within apredetermined duration from the first time: monitoring received audioinput to identify a second spoken input in the audio input, wherein thesecond spoken input does not comprise the spoken trigger; in accordancewith identifying the second spoken input, performing a second task basedon the second spoken input; and providing a second response indicatingthe performance of the second task.
 26. The method of claim 25, furthercomprising: while monitoring the received audio input, outputting avisual indicator, the visual indicator indicating that the electronicdevice is capable of responding to received spoken input not includingthe spoken trigger.
 27. The method of claim 25, wherein the secondspoken input is identified without identifying a physical or virtualbutton input received prior to identifying the second spoken input. 28.The method of claim 25, further comprising: after the predeterminedduration from the first time: ceasing to monitor for spoken input in thereceived audio input; and receiving a third spoken input, wherein thethird spoken input comprises the spoken trigger; and in accordance witha determination that the third spoken input comprises the spokentrigger, performing a third task based on the third spoken input. 29.The method of claim 25, further comprising: prior to performing thesecond task, determining whether to respond to the second spoken inputbased on contextual information associated with the second spoken input.30. The method of claim 29, wherein determining whether to respond tothe second spoken input includes evaluating one or more conditionalrules that depend on the contextual information.
 31. The method of claim29, wherein determining whether to respond to the second spoken inputincludes: calculating a likelihood score that a virtual assistant shouldprovide the second response to the second spoken input based on thecontextual information.
 32. The method of claim 31, wherein thecontextual information comprises an elapsed time between receiving thesecond spoken input and the first spoken input, and wherein calculatingthe likelihood score that the virtual assistant should provide thesecond response to the second spoken input based on the contextualinformation comprises: decreasing the likelihood score in response to avalue of the elapsed time being greater than a threshold duration; andincreasing the likelihood score in response to the value of the elapsedtime being less than the threshold duration.
 33. The method of claim 31,wherein the contextual information comprises the first spoken input, andwherein calculating the likelihood score that the virtual assistantshould provide the second response to the second spoken input based onthe contextual information comprises increasing the likelihood score inresponse to detecting a match between the first spoken input and thesecond spoken input.
 34. The method of claim 31, wherein the contextualinformation comprises an orientation of the electronic device when thesecond spoken input was received, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:decreasing the likelihood score in response to the orientation of thedevice being face down or upside down; and increasing the likelihoodscore in response to the orientation of the device being face up orupright.
 35. The method of claim 31, wherein the contextual informationcomprises an orientation between a user and the electronic device whenthe second spoken input was received, and wherein calculating thelikelihood score that the virtual assistant should provide the secondresponse to the second spoken input based on the contextual informationcomprises: increasing the likelihood score in response to theorientation being one in which a display of the electronic device isoriented towards the user; and decreasing the likelihood score inresponse to the orientation being one in which the display of theelectronic device is oriented away from the user.
 36. The method ofclaim 31, wherein the contextual information comprises an indication ofwhether the second spoken input was recognized by an automatic speechrecognizer, and wherein calculating the likelihood score that thevirtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: increasingthe likelihood score in response to the indication indicating that thesecond spoken input was recognized by the automatic speech recognizer;and decreasing the likelihood score in response to the indicationindicating that the second spoken input was not recognized by theautomatic speech recognizer.
 37. The method of claim 31, wherein thecontextual information comprises a semantic relationship between thesecond spoken input and the first spoken input, and wherein calculatingthe likelihood score that the virtual assistant should provide thesecond response to the second spoken input based on the contextualinformation comprises: increasing the likelihood score in response to avalue of the semantic relationship being greater than a spoken userinput semantic threshold value; and decreasing the likelihood score inresponse to the value of the semantic relationship being less than thespoken user input semantic threshold value.
 38. The method of claim 31,wherein the contextual information comprises an identification of aspeaker of the second spoken input, and wherein calculating thelikelihood score that the virtual assistant should provide the secondresponse to the second spoken input based on the contextual informationcomprises: increasing the likelihood score in response to the identifiedspeaker being included in a list of authorized speakers; and decreasingthe likelihood score in response to the identified speaker not beingincluded in the list of authorized speakers.
 39. The method of claim 31,wherein the contextual information comprises an indication of whetherthe electronic device was outputting information to a user when thesecond spoken input was received, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:increasing the likelihood score in response to the indication indicatingthat the electronic device was outputting information to the user whenthe second spoken input was received; and decreasing the likelihoodscore in response to the indication indicating that the electronicdevice was not outputting information to the user when the second spokeninput was received.
 40. The method of claim 31, wherein the contextualinformation comprises an indication of whether the electronic device isbeing held when the second spoken input was received, and whereincalculating the likelihood score that the virtual assistant shouldprovide the second response to the second spoken input based on thecontextual information comprises: increasing the likelihood score inresponse to the indication indicating that the electronic device wasbeing held when the second spoken input was received; and decreasing thelikelihood score in response to the indication indicating that theelectronic device was not being held when the second spoken input wasreceived.
 41. The method of claim 31, wherein the contextual informationcomprises a previous action performed by the electronic device, andwherein calculating the likelihood score that the virtual assistantshould provide the second response to the second spoken input based onthe contextual information comprises: increasing the likelihood score inresponse to the previous action performed by the electronic device beingone of a set of predetermined actions; and decreasing the likelihoodscore in response to the previous action performed by the electronicdevice not being one of the set of predetermined actions.
 42. The methodof claim 31, wherein the contextual information comprises an indicationof whether content was being displayed by the electronic device when thesecond spoken input was received, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprisesincreasing the likelihood score in response to the indication indicatingthat content was being displayed by the electronic device when thesecond spoken input was received.
 43. The method of claim 31, whereinthe contextual information comprises a semantic relationship between thesecond spoken input and content being displayed by the electronic devicewhen the second spoken input was received, and wherein calculating thelikelihood score that the virtual assistant should provide the secondresponse to the second spoken input based on the contextual informationcomprises: increasing the likelihood score in response to a value of thesemantic relationship being greater than a content semantic thresholdvalue; and decreasing the likelihood score in response to the value ofthe semantic relationship being less than the content semantic thresholdvalue.
 44. The method of claim 31, wherein the contextual informationcomprises a position of a user when the second spoken input wasreceived, and wherein calculating the likelihood score that the virtualassistant should provide the second response to the second spoken inputbased on the contextual information comprises: increasing the likelihoodscore in response to the position of the user being one of apredetermined set of positions; and decreasing the likelihood score inresponse to the position of the user not being one of the predeterminedset of positions.
 45. The method of claim 31, wherein the contextualinformation comprises a semantic relationship between the second spokeninput and the first response, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:increasing the likelihood score in response to a value of the semanticrelationship being greater than a semantic threshold value; anddecreasing the likelihood score in response to the value of the semanticrelationship being less than the semantic threshold value.
 46. Themethod of claim 31, wherein the contextual information comprises asemantic relationship between the second spoken input and an applicationbeing run by the electronic device when the second spoken input wasreceived, and wherein calculating the likelihood score that the virtualassistant should provide the second response to the second spoken inputbased on the contextual information comprises: increasing the likelihoodscore in response to a value of the semantic relationship being greaterthan an application semantic threshold value; and decreasing thelikelihood score in response to the value of the semantic relationshipbeing less than the application semantic threshold value.
 47. The methodof claim 31, wherein the contextual information comprises a movement ofthe electronic device, and wherein calculating the likelihood score thatthe virtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: increasingthe likelihood score in response to the movement being one of apredetermined set of movements; and decreasing the likelihood score inresponse to the movement not being one of the predetermined set ofmovements.
 48. The method of claim 31, wherein the contextualinformation comprises a direction of a user's gaze when the secondspoken input was received, and wherein calculating the likelihood scorethat the virtual assistant should provide the second response to thesecond spoken input based on the contextual information comprises:increasing the likelihood score in response to the direction of theuser's gaze being pointed at the electronic device when the secondspoken input was received; and decreasing the likelihood score inresponse to the direction of the user's gaze being pointed away from theelectronic device when the second spoken input was received.
 49. Asystem, comprising: one or more processors; memory; and one or moreprograms, wherein the one or more programs are stored in the memory andconfigured to be executed by the one or more processors, the one or moreprograms including instructions for: receiving a first spoken input,wherein the first spoken input comprises a spoken trigger and requestsperformance of a first task; in accordance with a determination that thefirst spoken input comprises the spoken trigger; activating a virtualassistant operating on the electronic device; performing, by theactivated virtual assistant, the first task based on the first spokeninput; and providing, at a first time, a first response indicating theperformance of the first task, wherein providing the first responseincludes providing at least one of audio output and displayed output;within a predetermined duration from the first time: monitoring receivedaudio input to identify a second spoken input in the audio input,wherein the second spoken input does not comprise the spoken trigger; inaccordance with identifying the second spoken input, performing a secondtask based on the second spoken input; and providing a second responseindicating the performance of the second task.
 50. The system of claim49, wherein the one or more programs further include instructions for:while monitoring the received audio input, outputting a visualindicator, the visual indicator indicating that the electronic device iscapable of responding to received spoken input not including the spokentrigger.
 51. The system of claim 49, wherein the second spoken input isidentified without identifying a physical or virtual button inputreceived prior to identifying the second spoken input.
 52. The system ofclaim 49, wherein the one or more programs further include instructionsfor: after the predetermined duration from the first time: ceasing tomonitor for spoken input in the received audio input; and receiving athird spoken input, wherein the third spoken input comprises the spokentrigger; and in accordance with a determination that the third spokeninput comprises the spoken trigger, performing a third task based on thethird spoken input.
 53. The system of claim 49, wherein the one or moreprograms further include instructions for: prior to performing thesecond task, determining whether to respond to the second spoken inputbased on contextual information associated with the second spoken input.54. The system of claim 53, wherein determining whether to respond tothe second spoken input includes evaluating one or more conditionalrules that depend on the contextual information.
 55. The system of claim53, wherein determining whether to respond to the second spoken inputincludes: calculating a likelihood score that a virtual assistant shouldprovide the second response to the second spoken input based on thecontextual information.
 56. The system of claim 55, wherein thecontextual information comprises an elapsed time between receiving thesecond spoken input and the first spoken input, and wherein calculatingthe likelihood score that the virtual assistant should provide thesecond response to the second spoken input based on the contextualinformation comprises: decreasing the likelihood score in response to avalue of the elapsed time being greater than a threshold duration; andincreasing the likelihood score in response to the value of the elapsedtime being less than the threshold duration.
 57. The system of claim 55,wherein the contextual information comprises the first spoken input, andwherein calculating the likelihood score that the virtual assistantshould provide the second response to the second spoken input based onthe contextual information comprises increasing the likelihood score inresponse to detecting a match between the first spoken input and thesecond spoken input.
 58. The system of claim 55, wherein the contextualinformation comprises an orientation of the electronic device when thesecond spoken input was received, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:decreasing the likelihood score in response to the orientation of thedevice being face down or upside down; and increasing the likelihoodscore in response to the orientation of the device being face up orupright.
 59. The system of claim 55, wherein the contextual informationcomprises an orientation between a user and the electronic device whenthe second spoken input was received, and wherein calculating thelikelihood score that the virtual assistant should provide the secondresponse to the second spoken input based on the contextual informationcomprises: increasing the likelihood score in response to theorientation being one in which a display of the electronic device isoriented towards the user; and decreasing the likelihood score inresponse to the orientation being one in which the display of theelectronic device is oriented away from the user.
 60. The system ofclaim 55, wherein the contextual information comprises an indication ofwhether the second spoken input was recognized by an automatic speechrecognizer, and wherein calculating the likelihood score that thevirtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: increasingthe likelihood score in response to the indication indicating that thesecond spoken input was recognized by the automatic speech recognizer;and decreasing the likelihood score in response to the indicationindicating that the second spoken input was not recognized by theautomatic speech recognizer.
 61. The system of claim 55, wherein thecontextual information comprises a semantic relationship between thesecond spoken input and the first spoken input, and wherein calculatingthe likelihood score that the virtual assistant should provide thesecond response to the second spoken input based on the contextualinformation comprises: increasing the likelihood score in response to avalue of the semantic relationship being greater than a spoken userinput semantic threshold value; and decreasing the likelihood score inresponse to the value of the semantic relationship being less than thespoken user input semantic threshold value.
 62. The system of claim 55,wherein the contextual information comprises an identification of aspeaker of the second spoken input, and wherein calculating thelikelihood score that the virtual assistant should provide the secondresponse to the second spoken input based on the contextual informationcomprises: increasing the likelihood score in response to the identifiedspeaker being included in a list of authorized speakers; and decreasingthe likelihood score in response to the identified speaker not beingincluded in the list of authorized speakers.
 63. The system of claim 55,wherein the contextual information comprises an indication of whetherthe electronic device was outputting information to a user when thesecond spoken input was received, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:increasing the likelihood score in response to the indication indicatingthat the electronic device was outputting information to the user whenthe second spoken input was received; and decreasing the likelihoodscore in response to the indication indicating that the electronicdevice was not outputting information to the user when the second spokeninput was received.
 64. The system of claim 55, wherein the contextualinformation comprises an indication of whether the electronic device isbeing held when the second spoken input was received, and whereincalculating the likelihood score that the virtual assistant shouldprovide the second response to the second spoken input based on thecontextual information comprises: increasing the likelihood score inresponse to the indication indicating that the electronic device wasbeing held when the second spoken input was received; and decreasing thelikelihood score in response to the indication indicating that theelectronic device was not being held when the second spoken input wasreceived.
 65. The system of claim 55, wherein the contextual informationcomprises a previous action performed by the electronic device, andwherein calculating the likelihood score that the virtual assistantshould provide the second response to the second spoken input based onthe contextual information comprises: increasing the likelihood score inresponse to the previous action performed by the electronic device beingone of a set of predetermined actions; and decreasing the likelihoodscore in response to the previous action performed by the electronicdevice not being one of the set of predetermined actions.
 66. The systemof claim 55, wherein the contextual information comprises an indicationof whether content was being displayed by the electronic device when thesecond spoken input was received, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprisesincreasing the likelihood score in response to the indication indicatingthat content was being displayed by the electronic device when thesecond spoken input was received.
 67. The system of claim 55, whereinthe contextual information comprises a semantic relationship between thesecond spoken input and content being displayed by the electronic devicewhen the second spoken input was received, and wherein calculating thelikelihood score that the virtual assistant should provide the secondresponse to the second spoken input based on the contextual informationcomprises: increasing the likelihood score in response to a value of thesemantic relationship being greater than a content semantic thresholdvalue; and decreasing the likelihood score in response to the value ofthe semantic relationship being less than the content semantic thresholdvalue.
 68. The system of claim 55, wherein the contextual informationcomprises a position of a user when the second spoken input wasreceived, and wherein calculating the likelihood score that the virtualassistant should provide the second response to the second spoken inputbased on the contextual information comprises: increasing the likelihoodscore in response to the position of the user being one of apredetermined set of positions; and decreasing the likelihood score inresponse to the position of the user not being one of the predeterminedset of positions.
 69. The system of claim 55, wherein the contextualinformation comprises a semantic relationship between the second spokeninput and the first response, and wherein calculating the likelihoodscore that the virtual assistant should provide the second response tothe second spoken input based on the contextual information comprises:increasing the likelihood score in response to a value of the semanticrelationship being greater than a semantic threshold value; anddecreasing the likelihood score in response to the value of the semanticrelationship being less than the semantic threshold value.
 70. Thesystem of claim 55, wherein the contextual information comprises asemantic relationship between the second spoken input and an applicationbeing run by the electronic device when the second spoken input wasreceived, and wherein calculating the likelihood score that the virtualassistant should provide the second response to the second spoken inputbased on the contextual information comprises: increasing the likelihoodscore in response to a value of the semantic relationship being greaterthan an application semantic threshold value; and decreasing thelikelihood score in response to the value of the semantic relationshipbeing less than the application semantic threshold value.
 71. The systemof claim 55, wherein the contextual information comprises a movement ofthe electronic device, and wherein calculating the likelihood score thatthe virtual assistant should provide the second response to the secondspoken input based on the contextual information comprises: increasingthe likelihood score in response to the movement being one of apredetermined set of movements; and decreasing the likelihood score inresponse to the movement not being one of the predetermined set ofmovements.
 72. The system of claim 55, wherein the contextualinformation comprises a direction of a user's gaze when the secondspoken input was received, and wherein calculating the likelihood scorethat the virtual assistant should provide the second response to thesecond spoken input based on the contextual information comprises:increasing the likelihood score in response to the direction of theuser's gaze being pointed at the electronic device when the secondspoken input was received; and decreasing the likelihood score inresponse to the direction of the user's gaze being pointed away from theelectronic device when the second spoken input was received.